While we're all complaining about the state of current games, what I really want is for games (especially RTS games, but really any game) to come with an API so I can build and test AIs. For example, I love the game Planetary Annihilation (I played its predecessor Total Annihilation a ton as a kid). But after a few dozen games, I began to think 'I wonder if I could just encode my strategy as a policy' - not even deep-RL necessarily, just a set of rules. But I can't even try because they don't have an API :(

DOTA had also decent API links as far as I recall.

Also, there's a lot of research on older games, see https://github.com/openai/retro for interfacing with NES/SNES/GBA/etc games.