The goal can be accomplished with help of a certain object, part of every good puzzle game, that is: a ball. That's right, my friend, a ball. Or loads of them, in this case. Ok, ok... I'll tell the whole story.
You, as a player, control a cannon which can catch a falling ball - and shoot it at those nasty blocks. When the ball hits the top of the screen - or a block - it becomes a block. When three or more blocks of the same color are connected to each other, they disappear. You shoot those balls and try to form groups of three-or-more blocks, thus clearing the level - a bit by bit. The final goal is to get the best possible record. There is a time limit for each level. Running out of time isn't that serious - the game continues from the next level. You just don't get all the possible points, that's all. Delirium keeps track of the best records.
There are three different "level packs" to choose from, 52 levels in total. Delirium supports user made level packs and the necessary tools are provided should you want to try making your own levels.