So I just picked up XCOM last week and I'm fully aware that I am addicted to it. The gameplay is tight and balanced (the A.I. cheats, dammit!), the progression is addictive, and the atmosphere is wonderfully tense. I love the game and it deserved its 8.5 as well as its multiple GOTY nominations (did it win any awards? If you know, please comment!).
However, there are some qualms I have about the game, and there are a few ways that I think could greatly expand on its replayability. Luckily, Firaxis has strongly hinted through several post-release interviews that they are working on a sequel (HOORAY!) and are looking to improve upon the first game. These are my suggestions.
1) More Maps
One of the things that makes XCOM so great is the tense atmosphere that the game creates while slowly moving through a fog of war shrouded battlefield. The map design in this game is top-notch, but a huge problem I have with it is that they like to repeat. A lot.
I'm in my first playthrough and I have played on the same map on three different occasions (actually, on two of those occasions it was the same mission, too. Just with different enemy spawns). I plan to play the game at least 2 more times (one on Classic and one on Impossible difficulty), and the game loses some of its tension when you know the map before walking into it.

But...how...? I shot this UFO down last night! It's back!
Another reason why I want more maps is because...well, they're so damn good. I would not mind waiting an extra month or three for the game if it meant I would (truly) not see the same map twice in two playthroughs. That would be awesome. It would be even better if we could get a random map generator that creates these great maps when a mission starts, but it seems that the crafting of the maps must be done by humans. And that's fine; I just want more so that I can keep the feeling of suspense on my second and third playthroughs.
2) More Enemy Types
OK, this one is also aimed at the vein of replayability (excuse me, but this game just screams at you to play it more than twice). To be clear; the amount of variations in the enemies here is great, but there's potential to make it better for subsequent playthroughs if, say...we didn't see them all.
I'll give an example. The very first alien you come in contact with in XCOM: Enemy Unknown is the Sectoid. For those of you who don't know, here's a picture:

Him? He comes in one piece, but then I turn him into pieces.
This little guy is the grunt of the game, and quickly becomes the least of your worries as you encounter enemies such as Chryssalids and the terrifying Ethereals.
Okay, so let's say that, in the sequel, on my first playthrough this "grunt" creature is a Sectoid. Good. But what if that only happened by chance? What if there were, say, 3 different "grunt" creatures I could have been given for my playthrough, and I only got to fight the Sectoids by chance? You would get the Sectoids for the entirety of the playthrough for continuity's sake, but let's say you play again. This time, instead of Sectoids you find a creature called a Lurker in your mission, and then Lurkers are the "grunt" creatures for your playthrough?
I feel that adding and then randomizing enemy types would be greatly beneficial to the replay factor of the game, possibly with a feature to start a game where you can select which creatures that you have already discovered that you want to show up in your campaign. I would want to play again and again just to see what else Firaxis created for me to kill (or be brutally murdered by, for that matter).
3) Flexible Weapon Upgrades
One of the most satisfying moments of the game is when you finally research a new gun to fire at the aliens. The only issue with that feeling is that, once you create the gun, you're done. There's no more for you to do with it. Sure, you can upgrade ammo capacity and such in the Foundry, but there's no way to modify each gun's stats for individual soldiers.
I feel like it's a missed opportunity. My favorite example of this element is in Fire Emblem: Path of Radiance where you could craft a custom weapon for one of your soldiers to equip. You could customize its stats and colors, and could even give it a cool name (or a stupid one). Of course, in that game you could just pay for the best stats on any given weapon type, so XCOM would have to do it differently for game balance, but I feel like it could be done.
4) A Story...Maybe?
This suggestion is out there, I know. XCOM isn't a game that's particularly built for a story: aliens are coming to do something bad to humans, and we have to stop them before said bad things happen. The skeleton of a narrative works for the game's structure. But what including a campaign that focuses on the experiences of a squad of soldiers? Their families, their past, their weaknesses and vices, etc. There's potential for a good character-driven narrative here, especially when you throw in that they could still be permanently killed. You'll care about them on the battlefield more, not just because they have really high hit-percentages and psionic abilities, but because you know their story and want to see it end.
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I know it's a lot I'm asking for, but with the first game out and the formula created, I feel like a good sequel to the series would try to significantly expand upon the first. This all being said, I'm on board with whatever Firaxis wants to do with the next (unnanounced-but-it's-so-happening) title.
What do you think? Am I completely off my rocker here, or do you agree with anything I said? What do YOU want in a sequel to XCOM?