But that's nonsensical. The CRT doesn't see the graphics pipeline of, say, an SNES, it just sees an analog signal. The graphics processing is done in the digital realm, not in the analog realm. If you want to simulate a CRT, all you need is a physical model and a digital image to display, which can come from Unreal, Unity, or whatever any other engine or program or whatever. It makes literally zero sense to write an entire engine to implement a CRT simulation.