This article is for co-op sessions where both players are trying to use a keyboard and mouse to play co-op games.
Unfortunately Windows treats all keyboards and mice as the same - the Windows OS has no way to tell which keyboard belongs to who, and neither can your game. You can try to turn the guest's keyboard into a virtual controller following this guide.
Without emulating a controller with the second keyboard, it's unlikely your game will accept input from two keyboards unless the game supports mapping player 1 to WASD keys and player 2 to Arrow keys for example.
In order to enjoy co-op, players must use Xbox controllers, or controllers that have software installed to support Xinput (Like the Dual Shock 4 + DS4Windows software on Windows). If controllers aren't working, please confirm that the guest computer is accepting input from the controller via html5gamepad.
Some games do allow one person to use a keyboard, and another to use a controller, but we recommend all players use controllers in all instances where possible.
We are using controllers, but they're not working?