In Balder2D, players control small probes which shoot tiny projectiles with which they try to destroy each other. It features a 2D overhead view of the playing field. Probes may be human or computer controlled.

A probe can perform the following actions:

* rotate
* fire projectiles
* "stick" to a wall
* push off of a wall

Players menuver their probes around the playing field by sticking to walls and then pushing off in a new direction, while trying to shoot the other probes and avoid being hit by projectiles.

Games may be configured to have a time limit, score limit, and/or life(respawn) limit.

* Time limited games have a timer in the upper left, which counts down, and the game ends when time runs out.
* Score limited games end when some player reaches the maximum score.
* In life limited games, the game ends when only one player remains