I recently got my Stadia code and fired up 'SamShow' in Chrome to test it out.
I quickly found that my mouse didn't do anything in-game. If I held Escape and brought up the "Do you really want to exit the game?" interface, my mouse worked there, but it seemed to be totally not captured within the game itself.
Does this game not support a mouse (even for the menus, etc), or is something wrong?
FWIW, I'm on a iMac (new model) with a Bluetooth "Magic Mouse". I have the latest Chrome update and MacOS version.