If 300+ ping, that pretty much limit the game to turn based or something where syncing doesn't play a big role. (ie like old MMO, even if you have high ping you can still play cause it's not necessary to sync up other players location right away, as everything is happening on the server and eventually sync up is fine. )

But yeah, I don't have good suggestions with 300+ ping. if you can find a region that's <100 ping than I would recommend Rocket League, since it's F2P.