Color Infection (1 & 2)
Color Infection and Color Infection 2 are a pair of puzzle games built on the useful Box2D physics engine. They feature a bare-bones presentation, no music or sound effects, and a color scheme that is arguably hideous. Their saving grace is a selection of incredibly devious puzzle designs, the kind that make you sit back and bask in their cleverness, even as they taunt you with arcane complexity.
The objective on each level is to turn all the yellow balls brown, by bringing them in contact with other brown objects. Your only means of interaction is clicking on stationary pink objects to make them disappear, thus setting various convoluted chain reactions in motion. Color Infection 2 (and one level in the first game) features green balls as well, which must be kept uninfected by the brown ones in order to beat the level.
Included are a few nice usability features: press the [number keys] to adjust the game speed, and in the sequel, pressing [B] toggles a primitive but considerate colorblind mode.
Color Infection's designer, Tapir, could probably use an artist collaborator to get these games looking a little more appealing, but his talent for diabolical contraptions makes him a blessing for those who enjoy watching the interplay of gravity, inertia, and friction. Other than an ill-advised run of nearly identical levels at the end of Color Infection 2, you'll just see one intriguing setup after another. This is just one stylish makeover away from being one of the coolest puzzle series around.