A full-blown port of the M1 scenario, Devil in a Blue Dress. I won't hype this too much, since it's my baby, but it contains 21 solo levels (painstakingly debugged), almost 7 megabytes of original artwork, and 2 megabytes of original sounds. If you've played the original, you'll find all-new puzzles, secrets, and enhancements. If you haven't, this should keep you busy for almost as long as Bungie's M2 scenario.

Because of it's extreme size, it's also available in floppy-sized chunks.