Gamepads should work out of the box, but if your gamepad doesn't work, you out of luck.
Try HTML5 version, there is a chance that gamepad will work with it.

Gamepad support won't improve!
Reasons:
- gamepad support implemented by a different person, not me
- I'm not actively working on this game anymore

On Android, I tested only this gamepad, and it worked perfectly. 

You can find it by searching for 'T3 Wireless Bluetooth Gamepad'. But keep in mind that, while looking the same, these gamepads may be different inside. So no guarantee that even this gamepad will work.

Do not buy the gamepad specifically for this game! And if you already have one, test it, and it will be cool (and helpful for other people) if you report here if it works or not.

Thanks for trying to help anyway Steelseriesxl doesn't work for gamepad.

Yeah, the Android gamepad support is sadly broken on my Kishi (and I suspect most devices) because even after I remap buttons, the mapping used for the menu conflict with both the default mapping and my custom mapping. E.g., if I try to use the whip by pressing B, I get the menu and the whip simultaneously and the jump button A will simultaneously exit the menu  and jump in the game :(. Probably a really simple bug to fix.