I'd like to be of more help, as plenty likely exist that are not distributed on the Steam platform (if you are anti-DRM, Steam won't be of value to you).
gog.com is usually DRM-free, I think. I'm not sure what their indie market is like, I'm sure it is quite sufficient. And there should be plenty available direct from developers, but I don't even know where to begin. I don't really pay much attention to that game market these days. Once in a while one catches my eye, but I rarely make many indie or 2D purchases.