During an Extermination run, I had alt-tabbed to look at something in a Firefox browser. I typed a quick query into the URL bar and every time I hit space, I selected a level-up/item/training option on the game in the background.
#Keyboard Inputs in Background
warm zinc
dim phoenix
Hi! We'll look into this. I believe it can happen when using Borderless Fullscreen and alt-tabbing to another window on the same display. For the time being, in case it happens more than once, please try switching to Fullscreen mode or alt-tabbing between windows one more time.