Terra Invicta, the X-com by ways of a grand strategy by the Long War folks is having a demo week on Steam. You can play a single faction for seven years.
Gotta say, as stupidly complex and overwhelming it is at first, it's pretty damn fun early on as you scramble to grab and hold allies and it's a big brawl in the dark as the factions slowly reveal themselves and their agendas. Then the aliens start fucking with stuff and the hold on territories solidifies and it turns into more of an economic management thing as you try to hold what you grabbed while developing your tech and capabilities to go and exploit space in some form before the aliens (which vastly outmatch you in terms of tech and weaponry) lock it all down. And this shit is involved in terms of systems and stuff you gotta keep track of. Getting shit into space is expensive and inefficent so you really want those orbital manufacturing capabilities, but that stuff is expensive to get going and before you get there you'll have to rely on shipping stuff off of Earth. Meanwhile, back on Earth you're having to deal with alien incursions, potential giant monsters and dumbass alien cultists who are actively trying to fuck shit up (in my playtrough they managed to somehow lock down China and it's now crawling with aliens which are starting to spill over into other countries).
And this is all before you get to designing and building your own starships to take the fight to the aliens, for which you'll need to consider a ton of things like the engines, do you want them efficient or do you want more power to be able to maneuver in combat, do you want kinetic weapons that have big damage or do you want stuff like missiles and torpedoes that have some targeting (but if it's low then the aliens can just dodge), or just not worry and go for pew pew lasers.
And the tech tree, hoo boy the tech tree. Since the game covers such a massive time scale and it insists on some semblance of realism there's a shitton of things to research. You have a stupid amount of just drive techs, all with their own little niches that you may or may not want or need to use. Like, to drive the point home, the tech tree has a compact view that hides most of the sub-techs so it doesn't lag out the game whenever you open the damn thing :V
Anyways, fun game, give it a whirl if you can since it's free. Can't wait for a full release myself.