One idea I had in another thread (this one:
https://openxcom.org/forum/index.php/topic,4317.0.html) is that the player commands a "special unit" of the aliens - you're not the aliens, you're just a elite unit with more leeway (so you can deploy mixed units and such). But because they've pretty much thrown all into the invasion, you're left with breadcrumbs to prove yourself.
So your first troops are human cooperators and the odd monster or alien - say, Cultists (disposable cannon fodder), MiBs (abilities varies like X-COM's), maybe some monsters. You're not even using elerium craft, but human craft from your allies, and maybe some human-alien hybrid tech. Sorry pal, but the other commanders are eating it all up.
What's your objective? Another player has entered the game. Strange(er) aliens are attacking and doing strange things. Your patrons like to remain convert, so they want you to use human puppets at first to find out what's going on (you don't show your best cards right at game start). Who are they? Well...
...remember the aliens from Apocalypse? Their star is about to go Supernova and they want out. "Out" means Planet Earth. Which you got dibs on. They don't seem to wanna talk (and by talk, I mean swear submission to you) about it. There can't be two alien dominations.
But you still have to fight the humans too, because there's a invasion going on, its a good way to test your forces and your competence. Failure to perform will result in your becoming nutrient sludge to feed your fellow clones.
Your starting foes are locals - farmers and ranchers, the odd militia, local police, gun-nuts, etc. Eventually you start fighting military types and the weakest Apoc aliens and their human thralls, then X-COM and other human organizations later on.
Here's some ideas from that thread:
Damnit I had a nice reply typed up to you guys but I lost it. GRRRRRRRR
Just some (mostly human) enemy suggestions for prospective alien plays, I will try to re-create the detail again later:
- Locals (badly-armed, numerous civvies, to fight in Harvest and Research, angry civvies in terror missions, etc)
- Inquisitors (crazy anti-alien cultists, want to destroy aliens and their tech)
- Men in Blue (police forces and investigators - noisey Mulder and Scully types - working for X-COM/Governments. A bit weak on weapons, but good on numbers. Eventually go full SWAT because screw you. Also, their "terror" unit could be Attack Dogs!)
- Military (soldier types, complete with tanks, jeeps, the works. Militaries of nations. Lags one tier of weapons behind X-COM)
- Gray Ops (mercs working for unscrupulous corporations, power-mongers, shadowy manipulators, ruthless dictators - EXALTish types - who want to steal the alien tech to become rich/powerful. Had an idea that they could use primitive cyborgs or something unscrupulous)
- Rebel Hybrids (human-sectoid hybrids who rebelled against alien overlords using a mix of alien and human weapons, and psi. Want to overthrown the Sectoids but don't trust pure humans not to kill them. Could be the Alien game's equivalent of Ethereals)
- Enforcer Androids (Enforcer Androids created by X-COM's Professor Able Standard. In this timeline, Enforcer program was not cancelled and sorta the ancestor of Apocalypse's Androids. Tough, strong, no psionic abilities but invulnerable to psi as well. X-COM's mutons, so to say. There's a mod somewhere that adds Enforcers to Open X-COM - https://www.openxcom.com/mod/x-com-enforcer)
I'm not sure how X-COM itself would deploy. Of course, it should be the strongest force, and constantly evolve. One cool idea would be to get a lot of X-COM vets and have them create "deployment mixes" - think of different numbers of differently-ranked troops with a diverse mix of weapons, strategy and AI. It would be especially interesting if X-COM had access not only to vanilla but the new weapons modded by the community that are often seen in mods - shotgun, assault rifle, flamer, sniper rifle, grenade launcher, etc.
If you're doing something that has the aliens fight other aliens as well (Rebel Aliens/Aliens vassals of Micronoids/TFTD Aliens vs UFO aliens), then it gets easier, but I tried to do my best in thinking. Could even add Apoc aliens if you feel like it.
There's also the issue of ships and alien missions, but I will talk about it later.
Another group of enemies I had an idea for were
YOUR dudes, but under Micronoid control. Imagine entire UFOs and then bases falling under Micronoid control. Eventually, they learn how to spoof being good little Sectoids (How do you do my fellow Sectoids! Praise the Ethereals and the Hive Mind!) and the Hive Mind gets scared as eff about it because it means they're the ones getting the other side of the alien infiltration game!!