Basic ideas for it. Could you tell me if any of this seems impossible currently?
New map, small randomised military base complex with a nice firing field somewhere. One building per map tile, a few weapon emplacements. A full squad (10) marines. Daemons enter from open field areas. Stupid goddamned daemons. Easy. Maybe some infiltrators in the base areas as well. Skulls/imps most likely.
Weapons: some as per normal or previously seen in other scenarios with stats tweaked. The shotgun and the BFG are the only ones I can see as remotely different from conventional Xcom style weapons.
BFG=mini handheld plasma nuke.
Shotgun=extended blast similar to plasma style, short range, different (black, small) particles, no projectile particle, no burn patch, crappy vs armour.
Shouldn't be too hard.
Armour: simple green, blue, red armours, stealing DoomRLs resistance scheme.
Enemies: Lots of enemies, several waves, finishing with a pair of bruiser brothers. Random enough to keep you guessing. The enemies will be easy to mod in, they'll just have to be tweaked for balance (although, this is a !!Fun!! scenario anyway).
The basic idea is to lose, but to put your score into positives by the amount of enemies you kill. Might have to put in knockback on a few weapons to keep daemon/skull waves back a bit. Mars will fall, but what a beautiful, bloody state you leave it in. The red planet indeed.
I'm keeping this one simple as my first mod, just to check on how hard it will be to put together. More advanced scripting etc can come later. Scaredy-cat scientists running from daemons, a base self-destruct that got auto-engaged, stuff like that. I'll have a go at a quick Syndicate mod to see how things like psi-mind-control (persuadotron) and augmentations/combat boosters work. (cybernetics/combat drugs: accuracy, TUs, something for brain). Those happy-killy combat drugs.......... Damn hippies.