Semi-real-time-strategy at it's almost-best.
Quite a while has passed since last of "our" generation lived on earth, so coming back to it in need of place to live is quite new stuff. But no worries, a replacement spacestation for our old one is found in earth's space, and it just happens to be similar enough to our old HQ to be taken over immediately. This is where you step in, and start setting your own foothold to the earth.
Since earth isn't uninhabitet, you'll have start dealing with'em. Since attacking isn't the most usefull way against possibly-friendly "races", diplomacy and co-operation are the alternatives. There are friendly people such as Cyborgs, Psionics and other human leftovers (it's said that all of'em are the human descents after what happened in UFO Aftermath, just bit...different.), along with hostile factions, such as Mutants and Cultists. The game moves on with it's own weight if you don't eagerly expand your own territory, by putting out help requests from friendly factions near you. They ask to do a mission in their land, and usually reward you with their land to your use as you see fit. On some places you can build up a base, where you can build up factories, laboratories and so on. Sadly, the space in these cities are so limited, that heavy specializing in cities is required.
By researching you find better ways to deal with the becoming menace, and eventually more of your planets history and alien's plan reveal more and more when the time goes by.
Battles are semi-real-time, meaning that you can pause the action whenever you like to do whatever you want with your soldiers, and when you've given your orders, you let the time run again and see what happens. However, it's not turn-based real-time, as in Laser Squad Nemesis, for example. Actions of soldiers are measured by their skills in weapons, moving speed, etc. For example, it's more usefull to equip a man, who's better with rifles, with a rifle, than equip the same rifle with a man who's better using a shotgun, if a shotgun is also available. Not only this makes playing more interesting when your soldiers aren't copies of eachother, but it also makes it usefull, since you can specialize your men/women to the arts of combat their good at.
Besides their skills, soldiers have attributes, that reflect on skills. Take strength for example; it affects to how much your guy can carry, but it also affects to your guy's moving speed and couple of other things in lesser degree. Add intelligence to your guy when he level's up, and it affects to his stealth, etc (can't remember it off-hand).
To prevent of making all your guys to resemble Universial Soldier (albeit with better cooling system and acting skills), there are several professions available. For example, you need a heavy weapon profiency (Gunman) to be able to handle machinegun's and heavier protection. Sniper rifle's can only be used by a soldier specialized into sniping, and so on. Professions require certain skill level on three skills, such as perception with other two skills needs to be at certain level until you can start your sniper training. There are three level's of each profiency, which add some somewhat-unique abilities to your soldier. By "somewhat-unique" I meant that while Gunman means you can use ultra-heavy equipment, also Level 2 Technician can do the same plus some more. Additionally, cyborgs get their own transplant "professions", and psionic's get their equivalent, more heavy on the mind-controlling side. However, since every soldier can have 3 different professions, they can still be more than just basic cyborgs or psionics.
At the beginning, weapons and especially ammunition are ver few and far between, so the first time I encountered and killed cultists, it felt like Christmas when I got four assault rifles and some boxes of ammo for'em, along with some other usefull stuff. I'm not saying aliens and mutants wouldn't drop stuff, but it's quite rare occasion to see a mutant holding a shotgun. Gladly, if you encounter one and kill it, whether you pick the shotgun from the ground or not, it's yours when the mission is over. Saves the time picking everything up when the mission end's.
Otherwise the weapon and gear are quite similar to other games of this genre. Lot of stuff. Got your different types of weapon, different add-on's to your weapons, different ammunitions, medkits and -packs, and later on when you research, some more powerfull weapons than earth hold's in the real world these days.
When you have your men and women geared, it's time for a mission. There are couple different types of missions, involving killing sufficient number of hostile units, escorting group of people to safety, retrieving stranded person/s and escorting them to safety, and later on some more. Reasonably enough diversity on the missions if you ask me, since battle is like half the game.
There are two things that bother me though, one of'em is quite well known too. First of all, your guys are bit...well, they're not all that flexible. Meaning that they don't appear like Navy SEAL's or anything like that when they move. Granted, later on they will move with heavy equipment, but since they walk and crouch the same without any gear, they look bit stiff for the action. Also there's lack of cover wherever you go. It doesn't seem to make a difference whether you show your whole torse or just your head from behind the box, you still get hit around the same. Altough I haven't got the time nor interest to follow how precisely that happens with every shot, but still it kind of feels like it doesn't matter. Shooting behind cover is one example where the soldier's stiffness comes in mind. I could also sort of complain about reaction speeds and shooting skills of people, but there has to difference between lvl 3 and lvl 7 guy, so it's acceptable and it can be worked around anyway.
The worst thing in the game though, is the repeated maps or whatever you'd call'em. I don't know if this is true, but it would appear that Sweden has copied a piece of land from England, tree by tree (or England did the same for Sweden, there's no real way of knowing). Definition of boredom? Play the same map with same mission, back-to-back. Add a random generator for heaven's sake, or at least 50 new maps or something, it get's boring quite quick. Add this and I'll be playing this game for years, seriously.
In short for the rest :
A.I of the opposition isn't great, but it works decently enough. Generally speaking mutants are easy (at least in the beginning), with the exception that they don't die easily. It sometimes gets a bit hilarious when three of your guys shoot a mutant uncounscious, and then they start shooting that knocked-out alien on the ground until it dies, and it takes seconds for it to die sometimes. Altough I haven't studied that mutant's body to discover it's weaknesses, so there might be a way to end'em more efficiently.
Graphics aren't great, but I guess they're good enough. Surroundings could look better though, but the characters look good enough while in battle. Granted, the graphics are dated, but considering the genre, they're not even close to being the most important thing.
Sounds are...well...not much to mention about. Music is less-than-basic, it's useless, but it didn't bother me that much. Fighting sounds are bit weak too, but they could be also worse than they are.
What comes to bugs, after patching the game to v1.2, I haven't noticed anything. Once when I changed weapon's name after modding it, items names turned to GUN_PISTOL_01 -style when I went from squad-screen to manufacturing and back, but it returned to normal when I went back to Geospace and came back, so no biggie. In around 12'ish hours of playing, the games has crashed only once. Loading times are tad boringly long, but nothing you couldn't hold your breath while waiting.
As a conclusion, I'd say while the game isn't as good as many of us would have liked, after the patches it's still quite good. Besides couple of tweaks to my own liking, only major thing I would add is the random mapping or just loads of new maps, in different sizes too, preferably bigger.
Other than that, the game doesn't come far behind of the other genre high scorers.