Presentation by Stuart Allen of FunkyPear at Mochi London 2011, a post mortem of the highly successful game Gravitee Wars.

1. Gravitee Wars
A Post Mortem
Speaker: Stuart Allen
FunkyPear.com

2. Part 1: Background

3. The Gravitee Series
● Gravitee 1 and Gravitee 2
● Golf in space
● Newtonian physics to simulate gravity
● Sponsored by Kongregate

4. Gravitee 1
● Released September 2007
● Approximately 5m - 6m plays
● Current Ratings
● Newgrounds – 4.22 (Front Page)
● Kongregate – 4.00

8. 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?

12. 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!

21. Part 2: Development

22. 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

23. 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?

24. 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

25. 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

32. 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)

33. 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

34. 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.

35. 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

37. Part 3: Response

38. 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)

39. 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

40. 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

41. User Complaints (3 of 3)
● Miscellaneous
● Intuitive movement – hard to control
● No multiplayer yet!

42. Revenue % Break Down

43. Thanks for listening! :)