The Witness, from Thekla Inc. and Jonathan Blow, caught the attention of a few of us at PC Perspective… mostly Allyn. Anywho, it's based on an island that you explore and solve puzzles along the way. I'm not talking about puzzles in the “Space Quest”, point-and-click adventure sense, but like, puzzles that you would expect to find in a newspaper, which unlock doors and turn on machinery when solved.

If that sort of game is for you, then you might want to check out a “demake” of it, called The Wit.nes. It is created by an indie developer who goes by the name Dustmop, for NES emulators. Being a game that's based on the NES platform, the entire virtual ROM is currently 40KB. (NES titles varied between ~8kB and ~1MB). It plays from a top-down perspective in its exploration mode, rather than first-person for what should be obvious reasons, but the puzzles are apparently quite faithful to the original style.

It's free and small, so check it out at their page if you're interested.