De Toren is by Kevin Oke, who also did Consumer CULTure and The Last Ace. Both those games had an off-kilter retroness about them; De Toren seems to be more of an effort to do something self-contained and reasonably polished in Game Maker.
Graphics are still quite retro -- pixellated tiles -- but this is a straightforward puzzle game. Some rows above you is a rest area; you must climb up the tiles of the tower to it while satisfying two conditions: time, and score. Each tile you traverse once earns you points, but retracing steps costs you, and some enemies will also cost you points if intercepted. If you get to the rest area in time and with adequate score, the next "level" begins, which is just more of the tower.
A simple structure, but not bad. And the music is pretty nice lounge-influenced drum-and-bass.