Big Bang Mini is a fixed-screen shoot' em up with a fireworks theme. It does not concern itself with a story: humorous enemies (clowns, snowmen, etc.) fly over cities and the player has to shoot them down. There are overall nine cities, e.g. Hong Kong or Luxor with a retro techno theme, with nine levels and one boss each.
The player's ship is restricted to the DS' lower screen while the enemies mostly stay on the upper screen. The controls utilize the touch screen: the space ship is directly moved with the Stylus (tapping and dragging it). Rockets are shot towards enemies independently from the space ship position by making an upwards movement with the Stylus. Both the starting position of the rocket and its angel is based on how the movement was performed. Over the course of the game the player also gains special abilities, e.g. creating a temporary wall to block bullets, which are activated with touch screen gestures.
The goal of each level is to collect a certain number of stars which are left behind (and fall down to the lower screen) by killed enemies. The difficulty with this task is not only that each hit by an enemy projectile is instant death (the level can be instantly restarted), but also that the player creates own obstacles: each rocket that does not hit an enemy explodes in a firework with deadly shrapnel. After beating a level, there is a connect-the-dots mini game which does not need to be successfully completed in order to proceed. It only rewards a firework and, when every one is beaten, access to relax mode which allows to create fireworks without fear of being killed.
After beating the arcade mode, the player unlocks two more modes: mission mode (replaying 25 old levels with new challenges like a time limit) and challenge mode (score attack for a online high score). When playing against another player, the DS is held sideways and both can send the opponent's projectiles back.