Discounting Steam because otherwise I’d be here typing for an hour listing all the cheap games I enjoyed from there.

Lufia 2 for the SNES, which was great because it was a prequel to Lufia 1, though it took me a couple years to finally track down a copy in the pre-internet days. I was pleasantly surprised to find out it was a prequel, and there are actually massive spoilers for the 2nd game in the intro for the 1st one, so I unintentionally played them in the right order!