The basic idea behind slimy blobs is simple; split (or repel) the attacking blobs into successively smaller blobs until they vanish completely. Blobs come in four different colors; red, green, blue, and purple. In order to split a blob it must be shot with a bullet having a matching color; a red bullet splits any red blobs and so on. When a blob is hit by a non-matching bullet the blob is repelled only (as opposed to being repelled and split when the colors match). Each time a blob gets past the defense and crashes into the shield surrounding the gun tower the shield energy (represented by its radius) is reduced up to a point where the game is simply over.
Slimy blobs combines action, strategy, and puzzle into one game. The action lies in the constant defense of the gun tower by splitting and repelling the attacking blobs. This is, however, complemented with more strategic or puzzle-like aspects which arise due to the fact that almost any action within the game comes with long-term effects as well as the short-term effects ("the action"). Splitting a blob, for example, produces two smaller and faster blobs each of which have to be dealt with at some later point in the game. Given that there are already several small blob splinters around the gun tower, it may be strategically more appealing to simply repel the blob and deal with it as a whole later on when the smaller splinters have been dealt with first.
In sum, the essence of playing slimy blobs lies in trying out various strategies in search for particular strategies that lead to high scores and a manageable defense situation (manageable number of blobs) for as long as possible. This task is made more and more difficult through the game as the number of blobs constantly increases. From this it also follows that the best strategy may be to change between different strategies during the game as the pressure upon the defender constantly increases.