I adore the Eyemaze ‘Grow’ series of games. They’re cute, gorgeously made, surreal and fun to fiddle with.
Mostly they involve adding a number of things in the order of your choosing and seeing what happens. There are usually one or more optimal solutions, but you shouldn’t let that stop you from just enjoying yourself and seeing what happens.
They’re Flash-based and not too heavy. You can enjoy them right now in your browser. Grow v3 has just been released.
Play them now. All of them!