There's an infinite superzapper romhack for Tempest 2000 done by CJ from Reboot, too.
I've done over 300 "new maps" rom hacks for Doom using the exact method for the two Doom 2 versions. Did more romhacks on both of those versions to add correct map names and a proper ending. Also, a ton of source code hacks for Doom weapons damage amounts, health amounts on bonus pickups, etc, as well as some MAJOR source code hacks done by a few others to include missing sounds, music, door speeds, teleporting demons, telefragging and so much more. Adding the Cyberdemon and Spider Mastermind were huge hacks-as well as a Jaguar only variant of the Spectre. There's a lot more but Doom 2 is exceptional bc it opened the door to possibilities.
Just need a romhack to stop the timer in Mutant Penguins so I'll quit losing repeatedly on the 1st stage when the robot blows his lid