Thanks everyone -- from a combination of your recs alongside trailers, reviews, and sale-prices, I'll be getting these for under $15.

***Gorogoa (that looks unique compared to nearly anything I've played before)

***GRIS (lots of recommendations here and looks like a gorgeous platformer)

***Ynglet (I just wanna see how this feels to move in this game)

***A Bird Story (plus the soundtrack for fifty cents -- I like the idea of a textless story, plus it:s by the people who made To The Moon and I'm not sure that I would like that game yet so this will give some insight into the company).