Fire TV 4K : CPU: Quad-Core 1.8 GHzRAM: 2GB DDR4OS: Fire OS 7 (android 9)Storage: 8GB Version of DOOM : GZDoom-AndroidFreedoom for Android Support OpenGL ES 1.1/2.0/3.0/3.2 Sources: Freedoom-for-AndroidThe unofficial zdoom on Android thread