Sunday, April 29, 2012

Rapid Review of Books

I've been a member of a game design book club for almost two years now. We read books at a relatively slow pace, since we're all busy working on game projects.  That said, the book club has been one of the best sources of professional growth not just because of the book material, but the conversations they have inspired. Here is a review of books (some from my book club, some just personal reading) with an emphasis on evaluating strictly from a game design point of view.

The Art of Game Design: A Book of Lenses

Lots of good solid advice, and Jesse obviously has a lot of experience.  If I were ever going to teach a game design course, I'd probably choose this as the textbook.  Even if I'm not excited about every "lens" in the book, there's enough material to justify the price.

I have on more than one occasion considered buying a deck of cards with all the lenses, so when you're stuck on a problem you can pull out a lens to look at your design problem from a different perspective.


This book holds lots of revelations on human behavior, but aside from all the  interesting insights, the most enlightening lesson I got out of this book is the author's approach to data.  The creativity demonstrated in finding ways to test theories that would be otherwise difficult or impossible to test is impressive and inspiring.  Often as a game designer you have reams of data available but you need to ask the right questions to make sense of that data.  This book cleverly illustrates how data can be used in the right hands.
Predictably Irrational

I absolutely love this book.  If you watch at all, hopefully you have seen some of Dan Ariely's videos.  If you haven't, go watch some right now.

The book expands on the concepts presented in the video.  If the video was enough for you, great - but there's a decent amount of new material and depth compared to the video and it's an incredibly easy read.  If a designer ever wonders why our players ever act so "crazy" sometimes, this helps put things into perspective.
The Design of Everyday Things

This is a classic.  I read it back in one of my second year Engineering courses and  it has significantly influenced the way I see the world.  When somebody asks me "Do you have any book recommendations for becoming a Game Designer" this is pretty much the first book I recommend.  My book club chose to read it, so I took the opportunity to re-read it.  I was a bit discouraged by how dated some of the examples have become.  Although the concepts are timeless, some of the examples aren't relatable to an 18-year-old because they haven't had personal experience with things like watches, phones with cords, or fax machines.
Flow: The Psychology of Optimal Experience

The fundamental premise of this book is critical for any game designer to know, but reading the whole book is not required.  The lesson is so foundational, it is repeated in at least 3 other books on this list.  Every game designer should familiarize themselves with the concept of Flow, but not everybody needs the gruesome detail this book offers.
Drive: The Surprising Truth About What Motivates Us

Most of the lessons from this book can be extracted from videos on the internet based on the author either raw or there is also a great annotated versions.  There is also a matching TED talk with similar content but is a lot funnier.  Watch both and you won't need to read the book.

Awesome content?  Yes.  If you're intrigued and want to look further, I'd actually recommend Punished by Rewards instead.  I am completely obsessed with extrinsic vs. intrinsic rewards as a result of these books.  Chris Hecker gave an awesome talk at GDC in 2010 "Achievements Considered Harmful?" that drew some connections between Motivation and Game Design.

How We Decide
This was my favorite book of 2011.  There are mountains of Game Design lessons in here.  If Sid Meier is quoted as saying a game is a "Series of interesting choices", shouldn't we take the time to learn how humans go about making those decisions?  What happens when I have to decide under pressure?  How much does presentation matter?  How about the user's mood?  What happens when players have more choices?  Fewer choices?  No choices?  Irrelevant options?  How does information affect choices, social situations, context?

If you're not sure whether you want to invest the time, watch this video first, if it strikes your fancy - get the book - you won't regret it.

Mistakes Were Made

This book surprised me with it's relevance to game development.  Though it contains no direct game design lessons, it contains the secrets to being a great game designer.  Here are some qualities I look for in a great designer that are touched on in one form or another in this book:

  • Willingness to take risks, a willingness to fail.
  • Takes feedback well from other people
  • Understands that not everybody thinks the same way as you, and being able to see things from another person's perspective
  • Self-awareness of how our own biases affect our decision making.  The worst of which is "confirmation bias", our natural tendency to selectively hold on to evidence that confirms our pre-existing notions and views rather than taking a genuinely objective view on problems.
  • The humility to admit when you were wrong, with the ability to quickly refocus on constructive solutions - as well as the grace to let other people back down from positions they held.

Saturday, April 21, 2012

Twin Paladins

The latest Tribes patch buffs Dwarves quite a bit.  Today I'm going to present my favorite way to play the Dwarves: Pumped up Twin Paladins!

The goal is to reach a point where I have a pair of fully upgraded Paladins.  They'll have Shield, Helm, Sword and be within range of each other to heal. 

Fully upgraded paladins are fearsome. 
  • They have 1200 health
  • Their aura buffs each other to 35% Armor and 35% magic resist
  • Their mutual aura also buffs each other to 315 damage
  • They heal for 600!
She's too sexy for this blog
To reach this point nowadays I play my Dwarves a little differently than what I've seen most people do.  A lot of people I've seen have super upgraded Annihilators, Grenadiers with Swords standing on red squares, etc.  To be sure, these approaches are super strong and win games and I will very often play my games this way if the opportunity presents itself.  In the absence of a clear opportunity, early game I focus on dumping a lot of units out onto the board.  If there are opportunities to gain an AP advantage then I'll take it.  Gaining an AP advantage mostly consists of trading units, or finding ways to do more than 400 damage per action point through AOE and red swords.

Throughout this process though I try to avoid using any of my swords, shields or helms on anything but paladins.  My first paladin is the most vulnerable, and I'll keep her in the back, load her with helm and shield early, and drink beer as necessary to keep her alive.  The goal is to cycle as many cards as possible while keeping a reasonable AP efficiency against your opponents actions until you can get to your second paladin.

Here's a game that ended on the final units, but my upgraded paladins carried the day.  Besides, what could be better than 2 Paladins?  How about 3 Paladins?  I hadn't saved any swords, but I guess when you have a scroll, who needs swords?
No swords, but I have a scroll

I'm sorry your necro is useless against 35% Magic Resist.  No wait.... I'm not.
Moar Paladins!
You can't cycle too fast, as you will definitely give up too much if you simply let your opponent use all 5 actions a turn stomping on your units or crystals, position so you're not a super attractive target, but make sure you're cycling through.

Much like the end game Wraith for the Dark Elves, end game Paladins are extremely difficult to stop without  bursty damage.

Here's a game from before the Tribal Patch

My crystal is lower but my twin paladins are in position
And now I'm going to win....

Now with the Tribal patch, 1200 health with both 35% armor and 35% magic resist is 1846 effective health (1846 damage must be done to kill her). Keeping in mind a stomp, this means an enemy needs to do 1850 damage in 4 actions.  Even an Archer with a sword (450 damage per attack) is only going to do 1800 in 4 actions

This strategy has proven to be ridiculously effective against Dark Elves.

  • The Dark Elves have trouble doing much burst as their Impaler (300 damage) only has range 2
  • Their "nuke" in the form of Soul Harvest is not really a damage dealer
  • They do not have much physical armor, which makes them more vulnerable to the Paladin's swings
  • The only unit which even comes close to posing a threat is a fully upgraded Wraith, which is easily disposed of with the assistance of your Pulverizers.

This strategy is also effective against Humans and Dwarves.  Dwarves can sometimes 'cause a problem depending on how you each use your scrolls and Pulverizers, but here's a game I played recently where my opponent did standard play with Annihilators, Sworded Grenadiers, etc. and I went as quickly as I could to triple upgraded Paladins

Double Paladins has been least successful for me vs. Tribe.  The Tribe Grunts are the most effective killers of the pumped up Paladins, combined with burst damage from Bloodrage and/or meat they can often stomp even fully upgraded Paladins.  In addition the Tribe Chain Heal is very effective in the early/mid game for counteracting any AOE moves the dwarves try to try and squeeze out a gradual AP advantage, so clogging the board with lots of units is not always working in your favor.

Sunday, April 15, 2012

The Way of the Chain Lightning

Which way does Chain Lightning bounce?

The question that has plagued the curious since the dawn of Hero Academy.  At first I thought it was deterministic, but the Chain Lightning started bouncing different ways depending on how I cast it.  I finally decided it must be random within a single turn, with an RNG seed being passed along each turn.

But then a comment from sands got my attention. I was preparing to refute his point, and started doing some testing to support my case, but then quickly realized sands was right, the Chain Lightning is deterministic - and hours of data collection later, I present it here for you!

The way Chain Lightning bounces depends on the direction that you initially fire.  Depending on which way you shoot first, you then get a "jump priority table".  For every jump the lightning will start at the beginning of the list and look for targets.  The first direction that presents a valid target is the direction the chain lightning will bounce.

If you shoot West: W, N, S, NW, SW, NE, SE, E

If you shoot East: E, N, S, NE, SE, NW, SW, W

If you shoot North: N, E, W, NE, NW, S, SE, SW,

If you shoot South: S, E, W, SE, SW, N, NE, NW

If you shoot NorthEast: N, E, W, S, NE, NW, SE, SW

If you shoot NorthWest: N, W, E, S, NW, NE, SW, SE

If you shoot SouthEast: E, S, N, W, SE, NE, SW, NW

If you shoot SouthWest: W, S, N, E, SW, NW, SE, NE

Realistically, the way Chain Lightning bounces is just something players fiddle with on the turn the opportunities present themselves.  With the UNDO option available, it's usually just easiest to play around with casts from various angles until you get a result you like.  That said, maybe somebody will find a time to make use of this - mostly likely when you're playing against a Wizard and you want to position one of your units to minimize the bounce damage it takes.

A few implications of this
  • If you're not already, when you're shocking enemies into crispies with your Wizard, try shooting from different angles to see if you get more favorable results.
  • The bias of lightning to bounce east rather than west makes me think there's a minuscule advantage for playing Council from the left side.  I can't provide very good evidence for this, except to say that if you ever need your lightning to bounce to a third unit, it seems that bouncing towards your enemy's side has a more likely chance of finding that third target.
  • If you don't like the way Chain Lightning is bouncing, and you can't get any angle to work, go with a different approach, because the situation is not going to change on a future turn.  A bad bounce pattern now means a bad bounce pattern for as long as all the enemy units are in this shape.
  • If you are playing against Council, once in a blue moon you can set your units in a position that makes it slightly more likely for the lightning to terminate at a spot to which it can not do a third jump.  Your opponent will think they just hit some bad luck but you as the clever Council-Killer will know better.  Truthfully though, such a situation rarely comes up.
  • You are more likely to be able to set up a bounce-minimizing situation when assaulting from the second row from the top.  Since lightning has a bias to bounce northward, you are slightly more likely to be presented with opportunities to lead lightning on your lead unit to a north-side soaker.
  • Another way to use this knowledge to your advantage is to set up an East or North "lightning Rod" of units who can take it.  If your units are targeted by lightning it will probably bounce down the line.

Sunday, April 8, 2012

Detailed Stats on the Tribe

It's another New Race for Hero Academy!  Time to get dirty with some research.

Racial Passive
  • Bloodrage: Whenever a fallen unit is disposed by the enemy (stomped), the next attack by one of your units gets +50% damage on their next attack.  
    • For example,if a unit does 200 damage, the next attack will deal 300 damage
    • However, if your unit does 300 damage, the next attack will do 450 damage
    • The bonus is consumed as soon as any of your units with  Bloodrage performs an attack.
      • New units placed on the battlefield will not have Bloodrage
      • A newly placed unit that attacks will not consume Bloodrage on units that have it
      • The Bloodrage will persist through turns, and lasts until one of your Bloodraged units attacks.
      • The Bloodrage will also enhance a Shaman's heal, and using the heal will consume the Bloodrage
    • This bonus is received no matter how the body is disposed of, whether it's stomped, corpse exploded, turned into a Phantom by a Necromancer or Fireballed
    • Units can only benefit from one Bloodrage at a time.  If additional Tribe units are stomped, there is no effect on units who are already benefiting from Bloodrage .
    • You do not get this bonus if you dispose of one of your own units by stomping on it or exploding it
  • Classification: Fighter
  • Health: 800
  • Armor: 20%
  • Magic Resist: 0%
  • Movement Speed: 2
  • Primary Attack: Melee Attack
    • Used at range 1
    • 200 Physical damage
    • Attacking a unit below 50% health kills it instantly.
    • Attacking a crystal below 25% health kills it instantly.
  • Classification: Caster
  • Health: 800
  • Armor: 0%
  • Magic Resist: 0%
  • Movement Speed: 2
  • Primary Attack:
    • Used at range 3
    • 200 Magical damage
  • Secondary Attack:
    • Used on fallen units up to range 3
    • Can be used on friendly as well as enemy units
    • All enemy units in a 3x3 area around the corpse will take damage
    • The damage dealt is the same as attacking all enemies around the corpse with the Witch's next attack.
    • Therefore by default it will hit for 200 damage
    • However, if you have damage bonuses, the explosion damage will also be enhanced.  
      • If you have a Runemetal upgrade, the explosion will hit for 300 
      • Another example, if you have a Haunch of meat, you'll explode corpses for 550 damage
  • Classification: Support
  • Health: 800
  • Armor: 0%
  • Magic Resist: 10%
  • Movement Speed: 2
  • Primary Attack:
    • Used on enemies up to range 2
    • Deals 200 Magic damage
  • Extra Ability: Chain Heal
    • Heals the primary target for twice your attack damage
    • With the default 200 attack damage, the Shaman heals for 400
    • The heal can bounce up to two times (to a total of 3 targets)
      • Each bounce can travel up to 2 squares.
      • You can bounce through full health units to reach damaged units
      • Each bounce reduces the potency of the health by 50%.  So the heal amounts are 100%, 50%, 25%
      • The bounce cannot bounce back onto itself, nor can the heal bounce back onto the Shaman casting the heal.
    • Can be upgraded by elements that increase your attack damage such as Runemetal, Haunch of Meat, Attack Squares and Bloodrage. 
    • Can be used to resurrect fallen units.
      • Fallen units are resurrected for 25% of the heal amount as health.
      • For example, the basic 200 Attack shaman that heals for 400 will resurrect fallen units with 100 health
      • If a fallen unit is second on the bounce, it is resurrected with 50 health
      • If a fallen unit is the third unit on a bounce chain, it is resurrected with 25 health
      • If you use a Haunch of Meat to increase your attack to 550 (heal 1100) and resurrected a fallen unit, it will resurrect with 275 health (25% of 1100)
Axe Thrower
  • Classification: Shooter
  • Health: 800
  • Armor: 0%
  • Magic Resist: 0%
  • Movement Speed: 2
  • Primary Attack:
    • Used up to 2 range
    • Deals 200 physical damage
    • Deals 100 extra damage against targets who are above 50% health when the blow lands. Targets at exactly 50% health will not take the extra 100 damage.
    • This 100 bonus damage is not enhanced by any upgrades such as runemetal (Sword) nor the +175% haunch of meat
    • This bonus can be used alongside the +100 bonus from red sword tiles for a total bonus of +200 damage
    • The 100 extra damage is still mitigated by armor 
  • Classification: Super Unit
  • Health: 1000
  • Armor: 0%
  • Magic Resist: 0%
  • Movement Speed: 2
  • Primary Attack: Whirlwind
    • Used when at range 1
    • Deals full attack damage to the primary target and 66% weapon damage to all other enemies in a 3x3 area around the Chieftain
    • After dealing damage, the Chieftain then pulls in all enemies in a 5x5 area around him
    • If a unit cannot be pulled along it's path because of a unit blocking the way, it is not moved.
    • If there are two units that are both trying to close to the same spot, one of them will move and the other will then be blocked

      • It appears as though who slides first is randomly determined the same way chain lightning is deterministic within a single turn but random between turns. 
  • Secondary Attack: Charge
    • Used at range 2, 3 or 4
    • This ability is only usable in straight horizontal lines.  You cannot run at an angle.
    • Blocked by Line-Of-Sight; you cannot have any objects blocking you from the target
    • Chieftain runs up to the enemy and then does a single melee swing against the target for 200 damage
Haunch of Meat
  • Heals a unit for 700 and increases the damage of your next attack by 175%
    • Note that this is +175%, so you're doing almost triple damage
  • The bonus stacks multiplicatively with the Runemetal (Sword) upgrade.  For example, if your base attack is 200 damage and you have Runemetal (x1.5) and If you have a Runemetal (Sword) upgrade, your damage is 200 * 1.5 * 2.75 = 825 damage
  • As with scrolls, Red Square "Sword Tiles" apply their +100 attack bonus before the multiplicative bonuses. 
  • This bonus is also multiplicative with the racial Bloodrage bonus.
    • This can result in some pretty ridiculous damage.  Suppose you have a Witch, with Runemetal, a Haunch of meat, standing on a red square
    • Witch base damage = 200
    • Red Square +100 bonus = 300
    • Runemetal 50% bonus = 450
    • Bloodrage 50% bonus = 675 (notice it's 675 not 600, the two 50% were multiplied)
    • Haunch of Meat 175% bonus = 1856.25, which is rounded down to 1855

      • You want a piece of me?
    • Pushes all enemy units left or right, depending on where the Typhoon is dropped
    • Units on the row of the typhoon are always pushed backwards, units to the right of the typhoon are pushed forwards.
    • The exception to this rule is Typhoons dropped on the first column push all enemy units forward.
      • The main implication of this is there is no way to keep the first enemy column stationary while pushing forward all other columns.
      • In practice I have a hard time picturing when this will come up but grats to you if you find a way to take advantage of this - particularly if this let's you make a significant move while playing against the Tribe.
    Spike Armor
    • Increases health by 10%
    • Deals 33% of damage back to attackers
    • Spike Armor will not reduce the health of the attacker below 100
    • The reflection amount is based on the actual damage done after the defender's mitigation.  For example if you swing for 200, normally 65 would get reflected, but if the defender has armor mitigating the attack damage to 160, then the attacker only takes 50
    • The reflected amount is mitigated by the attacker's armor as well.  For example, if the attacker swings and hits for 300 damage, the normal reflect amount is 100, but if the attacker has 20% armor then the attacker only takes 80 damage
    • Putting these together, suppose an attacker with 200 attack and 20% armor attacks and defender with 20% armor.  The initial attack lands for 160 damage, and 40 damage is reflected to the attacker (50 damage reduced by 20% armor)
    • The reflect damage works against all attacks. In fact, the reflect damage even works against AOE spells such as the Witch's Corpse Explosion.  Damaging a unit with Spike Armor will hurt the attacker.
    • If a Warrior does an "instant kill" against a unit with Spike Armor, the damage done to the slain unit is reflected back for the amount of damage done (this may be obvious, but restating for clarity)
    • The damage type is the same damage dealt by the attacker. ie. Physical damage is reflected as Physical, Magic damage is reflected as Magic.
    • If you overkill a unit, the damage done to the attacker is only what was required to get the defender to 0.  For example, if a unit has 300 health left and you hit it for 500 damage, you still only take 100 damage (the reflect amount on the 300 required to kill the defender)
    The Tribe Deck Contents

    2x Chieftain
    3x Warrior
    3x Axe Thrower
    3x Witch
    3x Shaman

    4x Spike Armor
    3x Runemetal

    4x Haunch of Meat
    3x Typhoon

    Sunday, April 1, 2012

    Path of Exile

    The Path of Exile open beta was this weekend. I'm going to cover two of their systems: the Flask System, and the Item-based economy.

    The Flask System

    In Path of Exile you heal yourself with Flasks instead of Healing Potions.

    Each individual flask is an item that you can equip.

    Here's how the flask works.  Whenever you want, you can drink from the flask.  Using the above flask as an example
    • Drinking from the flask will heal me for 60 life over 6 seconds
    • Each sip uses up 7 charges.  As you can see this means I'll be able to sip 3 times before my flask is empty (21 charges total).
    • The flask refills itself slowly as you damage enemies. If you are standing around doing nothing, your flasks don't do anything, but if you are active attacking enemies the flasks slowly recharge.  The math for exactly how the flask charge-up is done isn't obvious right now - but it also doesn't matter.  It looks like they're doing some clever math under the hood so that it just works.
    • Removing a flask from your belt drains it of all charges

    The flasks are items that can get better.  For example it can heal you for more, or heal you faster.  Your flasks charge up when you kill enemies.

    This system works really well for a number of reasons.

    • You need to stay actively aggressive in order to refill your health potions
    • It gives a sense that not all enemiescan be beaten simply by buying sufficient potions.
    • It provides a healing mechanic under the player's control but still allows a limited degree of potion spamming as needed.
    What's really neat about the system is the flasks themselves can have magical properties, and they've come up with some really cool properties for them.  There's obvious ones like increased charges, and increasing healing potency.  You also have "Heals you 100% faster".  I got a flask last night that had "Heals for 50% of the amount instantly", which gives you a boost up front.  They also have "Heals you 125% faster when you are below 35% of your maximum Life".  

    That's just the "obvious" ones though, they took it a step farther and added temporary buffs.  They have everything from clearing debuffs, to increasing your resists, and reducing stun durations while a potion is active.  You can even get increased movement speed during the duration of the effect, which let's you move faster through the world a limited amount but you can't use it forever because of the limited charges, and you also don't want to use it too much or you'll be digging into your precious healing and mana pools when the time comes to fight. The possibilities are endless!

    To really complete the system, there are affixes that feed into the flask system for other body slots.  For example, you can get gloves that grant "22% increased charges gained for flasks" - so your other items can participate too - speeding up the rate at which your flasks refill.

    Bottom line: I really like their Flask System. I think it is clever, works well within their game, will probably be a huge hit with their audience, adds a lot of extra properties to their item game, cleanly addresses the potion spamming question without adding cooldowns, provides yet another method of item progression, lays the groundwork for some sophisticated combat.

    Item-Based Economy

    Path of Exile has embraced the notion of a trade and barter economy.  This is the sell window in Path of Exile.  Notice anything interesting?

    There's no gold!  When you sell your items to a vendor, they don't give you a gold price for your items, they offer you back mini-consumables!

    The basic units of currency include (but are not limited to):

    • Scroll of Wisdom - Identifies all blue items
    • Town Portal Scrolls - Creates an instant travel portal back to town
    • Armourer's Scrap - Improves the quality of armour
    • Blacksmith's Whetstone - Improves the quality of a weapon
    • Orb of Alteration - Reforges a magic item into a new set of random properties
    • Orb of Transmutation - Upgrades a normal item into a magic item
    • Orb of Alchemy - Upgrades a normal item into a rare item

    All of these are 1x1 inventory items that stack in your inventory.  I've only listed a handful here, there are many more.  Furthermore, many of the items are actually made of smaller parts (for example, Scrolls of Wisdom are composed from 5 Scroll Fragments).

    All of these objects are small 1x1 inventory objects.

    This premise even extends into buying items too!  Here are the tooltips on two items in the vendor "Buy" window:

    How crazy is that!  The developers took the idea of the "Stone of Jordan economy" and took it to the whole next level.  Now it's not just the high-end hardcore players trading in these 1x1 inventory items, but everybody who plays the game.  Path of Exile nails the basic premise behind an item-based economy- namely, players can use as currency any object that is a consistent commodity with universal value to most players.  This trade and barter economy is built right into the buy/sell interface at vendors


    • Promotes the lore of being on an abandoned island
    • Guarantees that you won't have a worthless gold currency (... durp)


    It places a heavy burden on inventory management.  Inventory management can be an important and fun part of RPGs.  More inventory space is something players always wish they had in the same way players want to pull the camera farther out, run faster and do more damage.  These inventory systems are in place for the player to butt up against and then make decisions. What does this have to do with Path of Exile's economy?  Since they are an item-based trade economy, your currency now takes up inventory space (like the D2 Stone of Jordan economy and D1 Gold).  As a concept by itself this is fine.  But having multiple types of trade items vastly increases the complexity to the player without adding any value.  There are so many different types of currency items it's easy to lose track of what's what.

    All these item slots taken up by 1x1 "currency" pieces makes me sad

    It doesn't leverage existing player expectations.  When it comes to game design, a game works better when the game does what the player expects.  If you're making a game entirely centered around "control stick left moves your character to the right, and control stick right moves your character left" then that's fine - but it means you should be basing your entire game on this concept and you should be prepared for the work it will take to retrain the user.  When you're going against your player's preconceived notions and biases you better be sure you're getting a good payoff for the cost.

    Ultimately, I don't think they've gained anything.  For all the player expectation breaking, is this actually working any better than gold? What did they gain?  Granted, in D2, gold was worthless, but is that a fundamental problem with gold or just a result of the way it was tuned?  For example, what if there were no Scrolls of Wisdom (identify scrolls), and every case in which they would have a Scroll of Wisdom, you replaced it with some gold.  You could drop 10 gold instead, and then charge 10 gold to identify an item.  The entire economy tuning done for identify scrolls would work exactly the same way except you'd be meeting the player expectations and removing the inventory headaches.