The screen is divided in half.
You get pairs of colored blocks (of four possible colors) dropped form the top of the screen and moving downward (while the same happens to the opponent in her half of the screen). You may rotate them and push them left or right, until they hit the bottom (or previously accumulated blocks).
Sometimes you get a "bomb" (in one of the four colors) instead of a block: when placed, it destroyes itself and all the connected blocks of the same colour (this may lead previously placed bombs to finally come into contact with blocks of their color, thus creating a chain reaction).
Whenever you manage to destroy some blocks in this way, the opponent gets an influx of extra black blocks (that will gradually become colored and may be then destroyed, but in the meantime engulf her portion of the screen). The amount of black blocks she gets depends on how many blocks you destroyed, their position and the chain reactions occurred, if any.
When your half screen is so filled that a new block cannot enter it, you lose.
While you play the puzzle game, in the middle of the screen goes on a battle between super deformed versions of your character and the character of the opponent; they are from Capcom's own "Street Fighter" and "Darkstalkers" series and behave and exchange blows based on how well you are faring in the puzzle part of the game (they have no impact of gameplay and are just intended as a cute visualization of how well the player is doing).
The game offers options to adjust various settings and also ulockable contents (extra characters, personalized icons for each character, an image gallery, etc.).