The default steam OS controls stop working whenever I enter the screen where you have to aim and throw stones at the plants. The only way to continue is to exit the game. Has anyone else run afoul of this problem and has anyone got a solution?

The game hides the mouse cursor. It has its own (big) cursor, but that does not respond to keyboard. (I tried WASD, arrow keys, keypad, random buttons) and does not respond to mouse. I even tried a gamepad, which did move it to the left, but when I let go it zoomed back to the right. Unable to play at all, and certainly can't hand it off to my 5-year old....