Rollaround

In Rollaround you roll around (surprise) 20 levels, in a game which comes across as a more cerebral version of Marble Madness. The twenty levels each feature 9 screens worth of squares, with no scrolling across them as such. On each level you are set a target number of crosses of each colour to collect, with less and less leeway as to how many of the different ones are required as the game goes on. There are pre-programmed moving enemies on each level to plan around, but the level's blocks vary in many ways. There are holes on the levels, but these can be jumped by pressing fire. You can turn plain squares into either crosses or holes, both of which invert the status of the crosses and holes respectively as well. Mystery squares (whose effect can be good or bad) and clock squares (which stop the timing and slow the aliens) are also present.