Here are my suggestion summary: 

1. Add Teleport move mode, since some of my friends got motion sickness easily.

2. Support bluetooth gamepad, such as XBOX series s/x joysticks, since a lot of good retro arcade games need more than 2 buttons.

3. Long-term: Full hand tracking without touch controllers, it should be amazing and make the best immersive experience.

4. Long-term: Multiplayer mode: If all of the players have the same rom file, then they can play the same game at the same time in PvP or Coop mode. (Up to 4 players, I think, since Dungeons & Dragon is my favorite beat ‘em up game…lol)