Gravitee Wars A Post Mortem

Speaker: Stuart Allen

FunkyPear.com

Part 1: Background

The Gravitee Series ●  Gravitee 1 and Gravitee 2

●  Golf in space

●  Newtonian physics to simulate gravity

●  Sponsored by Kongregate

Gravitee 1 ●  Released September 2007

●  Approximately 5m - 6m plays

●  Current Ratings ●  Newgrounds – 4.22 (Front Page)

●  Kongregate – 4.00

Gravitee 2 ●  Released August 2009

●  Approximately 4.5m - 5.5m plays

●  Additional game modes & improved graphics

●  Current Ratings

●  Newgrounds – 4.00

●  Kongregate – 4.05

●  Lower than Gravitee 1 – Original gameplay diluted?

Gravitee Wars ●  Original concept for Gravitee 1

●  Change of gameplay from golf to artillery

●  Concerned about alienating original players

●  Weapons and violence seem to do well!

Part 2: Development

Initial Thoughts ●  Single player planned since day one

●  Multiplayer possibilities for future games

●  Unit personality

●  Destructible planets

●  AI quality important

●  Cheap gameplay ●  Medals, achievements & rewards

Destructible Planets (1 of 3) ●  Each planet originally a bitmap, with explosions

being removed from the bitmap

●  Simple implementation

●  How to get units to walk around planets correctly?

●  How to calculate the new planets mass after an explosion?

Destructible Planets (2 of 3) ●  Planet shape stored as a series of points

●  Planets made up of about 40 points

●  Units walk around by following the line represented by two consecutive points

●  Shape drawn to a Movieclip then used as a mask over the planet graphic

●  Vector representation means mass easily calculated

Destructible Planets (3 of 3) ●  When a planet is hit, another series of points

representing explosions created

●  Function takes the explosion and planet shapes and cuts the explosion shape out of the planet

●  Calculates intersections between the shapes

●  'Walks around' each shape until it intersects the other shape, then switch shape and continue until back to origin

Cheap Gameplay ●  Wanted to use 'cheap gameplay' to keep

players playing

●  Better medals awarded for better scores

●  Achievements

●  Rewards

–  New weapons –  Unit victory and idle animations –  Features (old school GFX, infinite ammo)

Unit Movement ●  Units can walk around planet CW/CCW

●  Started with Right = CW, Left = CCW

●  Makes less sense when at the bottom of a planet

●  Decided to try to 'guess' which way the player wanted to move

●  At top of planet R = CW, L = CCW

●  At bottom of planet L = CW, R = CCW

Artificial Intelligence (1 of 2) ●  No experience with AI!

●  Various stages

●  Are there any pickups I can get?

●  Am I directly in the line of sight of enemies? If so, is there somewhere I can retreat to after shooting that isn't?

●  Gravity set up too complicated to work out a power & angle to guarantee a hit.

Artificial Intelligence (2 of 2) ●  AI throws out 720 different shots (72 different angles,

10 different powers)

●  AI decides on which of those shots to take, based on who can be hit, how much health they have and what weapons are available

●  Each enemy team has an accuracy score. Shots are knocked off by a random amount, based on this score.

●  Originally if the AI couldn't hit an enemy it would move or teleport to another planet and try again

Part 3: Response

Response Overview ●  Very well received!

●  Hit the 1m gameplay mark after 6 days

●  Total plays to date approx 12m – 15m

●  Current Ratings

●  Newgrounds – 4.42 (Top 50 for a while)

●  Kongregate – 4.40 (Best of Nov 2010)

User Complaints (1 of 3) ●  AI Flaws

●  Enemies take too long thinking – fixed

●  Enemies walk over mines

●  Enemies are too accurate with their shots

●  Enemies don't use all of the weapons

User Complaints (2 of 3) ●  Balancing issues

●  Why don't the AI teams shoot at each other?

●  Money cheat – end score based on health remaining and damage done

●  After earning enough money, its easy to just meteor strike and nuke the enemy to death

User Complaints (3 of 3) ●  Miscellaneous

●  Intuitive movement – hard to control

●  No multiplayer yet!

Revenue % Break Down

Thanks for listening! :)