It's not really gameplay but : not rendering me deaf when launching the game for the first time, games need to have their volume down to 50% by default
I once made this argument to a game dev community on Reddit and was called crazy for it. There are games where I literally have to remove my headsets when they open. Devs that make games for pc should understand that pc users don't just use their pc to play games, but also for other things. So volume control is obviously tied to each individual app/program.
I would like it if all games launched a simplified settings menu first thing after you open them up, before any cutscenes or intros.