itch.io

For 3d: click "play 3d" in the main menu, enable the "use gamepad" checkbox (under the "player name" input), click the "config gamepad" button that appears, and follow the instructions. 

For 2d: click "play 2d" in the main menu, disable the "standard controls and mouse for player 1" checkbox, click the "config p1 gamepad" button that appears, and follow the instructions. 

Let me know if you have any problems!