Instead, ViZDoom, a ZDoom-based platform designed primarily for AI research, runs the engine and renders it headlessly. Every rendered frame is placed on the Windows clipboard as a bitmap and pasted onto the Paint canvas as a genuine document edit. Russinovich writes that an early version repeatedly overwrote the clipboard, sometimes replacing frame data before Paint had finished reading it. Because every frame is a real Paint edit, Ctrl+Z can move backward through them, while choosing File > Save produces a PNG screenshot. We've extensively covered the incredibly long list of things that can run Doom in one form or another.