The Fool's Errand by Cliff Johnson
Cliff Johnson's classic text adventure The Fool's Errand is now available for free, and it's so old it comes wrapped inside a Mac emulator, which is kind of wonderful. Taking place in a whimsical fantasy setting inspired by the Tarot cards, this is an interactive storybook that will seriously test your puzzling brain, even if it is slightly fiddly to play when compared to modern IF standards.
The Reprover by François Coulon, Hélène Moreau, Marius de Fugulely et al
The Reprover, or Le Réprobateur (which just sounds so much better) is an odd one. It's a text adventure, sorta, but without that much text. It's also an FMV game, but that FMV plays in a non-interactive window that only occupies around a quarter of the screen. It's multimedia, essentially, and it's the only game that comes to mind that mixes text, images, and video in such an interesting way. The fragmented story concerns a character named the Reprover, who is hired to follow people around and condemn what they're getting up to. Your role as the...well, you're an observer more than a player here, so really your role is to poke around in these small scenes, reading bits of text, clicking on images and video, and gradually piecing together a bitty story. (Via RPS)
Lingotopia by Tristan Dahl
It's very, very early days for this interactive language game, but I already see quite a bit of potential. You're a traveller in an alien city (that currently comprises a small stretch of street), and as you wander around you'll find several things to interact with, which will reveal a word in a foreign language after being clicked on. A couple of NPCs will also test your knowledge of specific words, via a fairly tough quiz that seems to assume a degree of training not yet present in the game. Many of its dictionaries are practically empty at the moment, so you'll want pick one of the more fleshed-out languages like German or Italisn for the time being—but even so, I imagine you'll come out of this having picked up a few new words. (Via Warp Door)
Howard Phillips Lovecar by Kurki Collective
It's a silly pun, perhaps the silliest, but anyway here's a game that features Howard Phillips Lovecraft riding around in a car, splattering cultists under his spinning wheels, or using a couple of guns to transform them into cultist mince. It goes on forever, and there's not much danger of death unless you stop stock-still, so the game ends when you've had your fill of vehicular cosmic horror mayhem.
Snail Party by MansterSoft
Snail Party is a game about repetition and slow advancement, and it's a really lovely bite-size experience because of that. Playing as a snail, yes a snail, you have to type commands to slowly CRAWL your way around, to maybe EAT that bit of food, to certainly CHEW that bit of food, and definitely to HIDE from that nasty caterpillar who's coming this way with the intention of gobbling you up. It's a good joke, having to repeatedly type, and type, and type to get anywhere or do anything here, and one that mirrors the snail's unhurried, and pretty respectable journey through life.