Fyonn
did their best!
I have now completed POOM.
I can confirm it is a number of completely new levels. The weapon list ends up being Fists, Shotgun, Chaingun, Plasma Rifle, Rocket Launcher. The final boss is a familiar face but, they gave the Cyberdemon a chaingun in addition to the rocket launcher, making keeping your distance a priority so it uses its much easier to dodge rockets instead.
I can confirm it is a number of completely new levels. The weapon list ends up being Fists, Shotgun, Chaingun, Plasma Rifle, Rocket Launcher. The final boss is a familiar face but, they gave the Cyberdemon a chaingun in addition to the rocket launcher, making keeping your distance a priority so it uses its much easier to dodge rockets instead.