Well, I also want the game to work with the c64 mini, so controls need to work with just joystick, and my solution for that is double clicking fire to set X on empty, or ? on filled, keep fire down and move stick to set multiple. For consistence I'll also try to support holding X or V while moving the cursor to set multiple. Turns out left shift + fire is a ghost key, so if any other kb solution causes ghost keys causing other effects I won't be able to...