Aquattack is a colour-matching game in the vein of Bejeweled. Players are presented with a grid (presented as a fisherman's net) of different coloured fish, which they must match together in groups of three or more to allow them to escape. A row or a column can be shifted along as many times as they like until a matching set is created. A fish that goes off the end of the grid is simply wrapped around to the front. Each game has a clock that counts down from one minute, each time the player creates a matching set, some time is added to the clock.

As the game progresses, additional obstacles are added, like more types of fish, to make finding matching sets harder and immovable blocks, that can only be destroyed through the use of bombs (which are generated by creating a set of 4). There is also a challenge mode that involves the giving the player specific goals to accomplish, rather than simply aiming for as high a score as possible.