I greatly enjoyed playing through the OpenDev this evening, but couldn't get my Xbox one for windows (plugged in thru USB-C) to work at all. Is this feature not yet ready? Very curious to see how this plays with a controller.

Gamepads are supported but not sure wich ones (i think at least 360, ps5 and switch pro so i assume yours should as well),

I'm not sure if it will work, but you can try in your steam library to go in ED Playtest properties with right click, znd then in Controllers section, disable Steam Input

It already did the trick in the past for me

I play with a PS4 controller and i had to go in the config properties and force the activation of the controller to make it work. Don't know if it can help some others but it worked for me.

Also worth noting that if the controller is not turned on before launching the game, the game may fail to recognize the controller, but just relaunching solves that. I've added that to the top of the Known Issues now, and sorry for not including it in the list initially.

I had this same issue this morning - but thanks for Gilduron's post I discovered an entirely different cause that it wasn't working:

I went to the Steam library and opened Endless Dungeon properties (right click > properties)

However instead of disabling steam input I clicked the link to Controller General Settings

For some reason the options for Xbox was disabled.in those settings.

Enabled it and closed out options then restarted the game.

Previously I had no input response even at the menus and I now I do.  I haven't played the game with it yet because I stopped to tell folks about what I just learned, but I'll be doing that now.