Thank you for the feedback! Upgrade collection is accomplished by using the hotkeys 1, 2, or 3, depending on which slot you want to put it in. I'll be sure to update the game page with control information. Thanks for playing!
Gotcha! That never occurred to me, you can also use WASD to move instead of arrow keys, where the number keys are closer. I'll look into better key options for the future though!
