Oh, I thought about a thread like this, but hesitated because it isn't indie. Luckily you didn't

I signed up for the beta some months ago, mainly because I wanted to have Fallout. I still didn't buy anything until they added Paypal 2 days ago! And then I saw it.. Hostile Waters! The game of my dreams! An excellent strategy-action-hybrid, similiar to C&C Renegade but singleplayer-only and clearly surpassing it there. Yet I never played it. 7 long years since release and only now I finally got it!
Anyway, I'm loving that and for the "Buy 1 get 1 free" coupon I got Fallout. Two brilliant games for $6. Steal, anyone?

If they continue adding such classics, I'll definitely buy lots more

I guess Outcast is also the next thing I'm hoping for. Never played it

Is there some kind of Demo you can download to confirm a game's working for you? Or do you just have to take their word?
They don't offer any demo versions (yet?). But they have a forum for each of the games, so if anybody has had problems with a game you may likely read about it and possible solutions there. I think so far the problems have been rather sparse, though. At least DOS games shouldn't be a problem, as I've heard they simply pack pre-configured DOSboxes with the games.