On A Distant Moon

Pretty much amazing. It's got classic ZZT action and puzzles all the way through and has a nice tonal mixture of adventure, wonder, and general silliness--with some sneaky and subtle poignant themes coming through the story--to say nothing of the amazing music and ascii-art environments and other artwork. If you want to know how to make a very complete ZZT adventure that knows pretty much exactly what it's doing start to finish, play this game.