Supaplex was once my favorite game. At that time, I didn't have internet access so there was no chance to get a hold of a level editor. I downloaded it only a few years later and in my free time made these 62 wonderful new levels.
They have got nice feedback since there are new puzzles making the player think and have fun. All levels are solvable without problem - they are about logical thinking, not about speed or coincidence. To prove it, I also made demos showing solutions to all the levels (these can be played back inside the game).