From the forum posts I found it's an issue with input devices like controllers. However "virtual" controllers cause this problem too. I used to use a gamecube emulator, and the virtual controller set-up caused this error.

I'm only telling you why this happens just in case you're good at troubleshooting and this guide doesn't help you, you have somewhere to start.

It doesn't really matter what type of controller you used or if you even remember using one, I'm going to show you how to fix the problem, and that's all that matters.

Unplug your controller. Unplug anything even remotely related to your controller.

That's it, the other solution is for people who have used emulators or similar programs in the past and are sitting at their computer frustrated because they don't have a controller plugged in and are still getting this problem.

The easiest way to open device manager is by using the windows search feature. If you have windows 10, you have to use cortana. If you have any other versions of windows, you can find the search bar just by hitting the windows key.
Type into the search box "Device Manager", and then click on the icon for device manager.Expand the section labled, "human interface devices"Now, I know that my giant circles may lead you to believe that I think you're an idiot, but you have to use your brain here, basically look for any devices in the list that look like anything other than your keyboard or mouse. You're looking for controllers, basically.
After you've found the devices that don't seem to belong in the list, right click on them and press "disable device".

Don't worry, all you should need to do is right click on the device again and click "enable".

Hopefully you're able to play the game now. If there's another way to fix this, I'd gladly add it to the guide so that more people can enjoy Voxel Turf.

Have a nice day!