I am serious. With some slight tweaking, there's some fertile ground here:

• Set the game on a populated Mars instead of Phobos/Deimos to preserve the basic game structure of intercept enemy ships/respond to terror missions/take out bases
• Plasma rifle/BFG 9000 as early game research options (equivalent to vanilla X-Com's laser rifle/heavy laser), use Doom 64's Unmaker and demon weapons as inspiration for late-game tech (heavy plasma/blaster launcher equivalent)
• In Doom and Doom 2 alone there's enough baddie variety to have a suitable roster of enemy units
• Even though the games mostly have heavy metal soundtracks, there are many songs that would make suitable geoscape music
• You could recreate the revenants' homing fireballs by just taking the blaster bomb code and reducing the explosion size/power
• Final research is opening a portal to Hell, final mission is invading Hell
• Absolute bullshit like a cyberdemon reaction firing and instantly wiping your squad would both preserve the authentic X-Com experience and reflect the effectiveness of non-Doomguy marines in Doom's lore

If only I didn't have a million other projects I already wanted to do.

It took the team years to finish because the game has so much text and they had to rewrite a significant chunk of menu code to accommodate the longer English words

Based Advance Wars teaching that it's perfectly okay to kill the footsoldiers of the bourgeoise

• Sonic the Hedgehog 2 contains data for a cut level called "Genocide City"
• Obscure Wolfenstein clone Corridor 7 randomly jumpscares the player with a red demon face during regular gameplay
• Dog Island, a Wii game in which all the characters are adorable chibi dogs, has a subplot about a doctor whose botched treatment caused the death of someone he loved many years ago. He still sees her in his dreams, unable to let go or move on.

"I'm fine with even my escapist fictional world revolving around profit, exploitation, and alienation but don't you DARE put a nonbinary person in it!"

• Weapons that keep killing long after the war they were used for is over (the Space Jockey isn't just dead, they're mummified, and there's no indication that there are any others of their kind around)
• Lay hidden and dormant, leading to innocent people stumbling on them by accident and getting killed (Nostromo crew finds the eggs and doesn't know what the fuck 'til it's too late, colony LV-426 gets wiped out because it was unknowingly built on top of a nest)
• They render entire areas unsafe to inhabit
• Aliens has often been considered an allegory for the Vietnam War, and that left enormous amounts of UXO across Southeast Asia that still persists today.
• The Weyland-Yutani and corporate profiteering aspect is a bit fuzzier, but I think there's a case to be made that their attempts to weaponize xenomorphs and the catastrophes this causes mirror the real-world military-industrial complex.

Disclaimer: I'm stealing these from Fred Clark's Left Behind Critique because I'm sure as hell not buying any of these books.