Well, if you're looking at remakish things, I remember a Game Boy Advance game that was sort of like what they are making now, called Rebelstar: Tactical Command
, which was like X-Com, but with only 8 characters at a time, named characters, a linear plot, scripted battle types, and no replacement troops, so you had to reload or restart the mission until you could do it with 0 casualties.
They also had an experience system where you gained 3 stat points every level, but which 3 stats were random, so you'd have to just reload until your riflemen got an accuracy point, because by the mid-late game, the basic sniper rifle was basically more powerful than any of the alien rifles, and you could shoot accurately to the limits of sight range with a snap shot, and it was even effective against saucers. (Of course, if saucers so much as SEE you in the open, you're basically dead, so that's pretty much the only way to take one down aside from a heavy weapon ambush.)
It wasn't as in-depth as the original X-Com, but for a game boy game you could take with you, it was pretty impressive.
There's also Silent Storm and Hammer and Sickle, which let you do some pretty crazy things with destructible environments and actually fairly cunning AI. (Guard a stairwell with a machinegunner? The AI won't rush up those stairs, but will hide in the floor below so your sniper can't pick them all off. But then, just stay quiet and listen for where they are converging, and plant C4 on the floor/roof above them, and blast a hole, and while they are still stunned, toss grenades into the hole... suckers!)
The only problem is the game had a difficulty curve that approached near infinite slopes - the first couple levels of Hammer and Sickle were basically "reload until you get really, really lucky", the middle levels were fairly easy once you had actual skills and specializations and could hit a target more than 2 tiles away with over 50% accuracy. (The game would literally miss with a pistol at a range of one tile, when the animation would put the hand of the character inside the torso
of the target, and in order to miss, the character would have to be animated literally firing the gun backwards
to get it pointing in a direction that wouldn't hit the target.) The final level, however, has you protect a target that dies in one shot and is standing right in front of 20 enemies with machine guns, while you are 80 tiles away. It's like the game is just f***ing laughing at you.