Three projects you may be interested in backing (or just looking at :):
--
Obduction by Cian, Inc., on Kickstarter. This is the latest opus of the
Myst series. For Windows and Mac. There is no demo and they're asking for a lot of money (well not so much compared to the kind of budget they used to have) and the smallest pledge allowing to get a copy of the game is $25. The campaign ends on Nov 16, though so if you're on the fence about this one you still have time.
--
Cornerstone: The Song of Tyrim by by Ascension Games on Kickstarter too. Shamelessly and hugely inspired by Zelda Wind-Waker. For Windows, Mac and Linux. You can download the demo. Smallest pledge for a copy is $10.
The campaign ends on Oct 26 so they may not make it. They did make it! Awesome!
--
Secrets of Raetikon by Broken Rules on Indiegogo. This is an exploration game in what looks like a quite colorful and original universe. You get access to the alpha if you back the project and I think you also get a free copy of their first game, And Yet it Moves, which was really good. I got one although I'd already bought the game when it came out so... The campaign ends on November 22. Smallest pledge is $10 and you don't get a refund if the campaign doesn't meet its end goal.
Edit:
Forgot
Treasure Adventure World by Robit Studios, an open-world platform game for Windows, which you can pre-order for $10. They're doing this on their own without going through KS or Indiegogo.