All 4 controller ports control Player 1 in Multiplayer.

[MrHardwick05]

I tested the Multiplayer mode with 4 Xbox 360 Controllers plugged in, but when I got in game, all 4 controllers were controlling Player 1 (White) instead of controlling the respective players, making this game impossible to play with friends, only possible to play against the CPU.

[Cheezball86]

Having the same issue. 2 8bit and 2 Xbox SX controllers, all controlling player 1. Hopefully this can get fixed, as this is the most exciting retro game I've been looking forward to!