I love jump n bump and i have 8 gamepads. Would be cool if 8 gamepads could be used in the game. Noticed that you use ReWired for input. According to documentation it's possible to switch off accessing the gamepads via XInput so you could access 8 XInput gamepads via DirectInput instead of only 4.
I think the most crucial thing for the platformer to feel more fluent is to so players don't stutter and get stuck when colliding with walls of objects.
Also couldn't get 8 players to work since gamepads and keyboard players control the same 4 players.
Keep up the good work!