The Dreamatorium of Dr. Magnus 2 - 5 keys - Open to all level 1+ -
No region restrictions to my knowledge - runs on Windows, MacOS, SteamOS/Linux - has cards

I recently topped-off my credit at DailyIndieGame and had credit left over. To be blunt, their selection isn't the best - they have quite a few games, but the Steam reviews and first impressions of them too often negative, in spite of the low prices. I chose this one as one rated Mostly Positive, in the 205th place on the community wishlist, and one that hadn't been given away for free in the past. I hope those who win will enjoy it.

I have a feeling much of what DIG offers will eventually be given away for free at some point, erasing CV from the giveaway, but if anyone has any recommendations as to what on their site might make a good giveaway, I still have some credit leftover that can go toward giveaways. Good luck & have fun!