basically you just need to get 3 balls of the same color to touch, and they dissappear. the real game will be tetris-style, where you are fighting to keep the playfield from overflowing (right now it just keeps it filled for testing).
also it's really easy right now, so I think I'll up the requirement to at least 4 balls touching. I of course will add a score system that gives big bonuses for combos

SCREENSHOTS
SHOT 01
SHOT 02
GAMEPLAY VIDEO
DIVX AVI - approx 1.2MB
the game is a testament to the Newton material system. everything is done with materials, from allowing balls to pass through the glass, to knocking other out, to checking it balls are touching, etc! most of the "brains" of the game are in a single material callback

it's been fun coding this, because using proper physics makes the gameplay very intuitive, and also posed some challenges for determining when to destroy balls that are touching, as there's no easy array-based way to do it, like a standard 2D puzzler would use.
any comments welcome!