SummaryAliens + Weapons + Explosions = Fun
The GoodThe best part for me was the actual combat. Being able to choose between realtime mode and turn based mode is a nice feature, although I have to admit I've only ever played in turn based. I tried realtime and it wasn't to my liking. Playing in turn based mode I was able to take my time and methodically comb through a building. The different aliens demanded different tactics to deal with them. When going after a multiworm, for example, I didn't fire at it, but instead positioned my agents around it, then ended my turn. When the aliens had their turn, my agents used their remaining time units to fire on the multiworm, hopefully not actually killing it outright. Then when it was my turn again I had full control of my agents to deal with the four hyperworms that popped out of the dead multiworm (this usually meant trying to kill them all with one explosive round from an auto-cannon). On the other hand, the only strategy you need to kill a Spitter is to shoot it a couple times, or in the case of a Psimorph, to hide. The combat really makes this game.
The research helps develop the story at a good pace, and also allows you to make better weapons (and use the aliens weapons against 'em). Better weapons helps you deal with the powerful aliens that show up the farther the game goes. Trust me, if you don't use these new weapons, you'll feel a bit silly trying to kill a Megaspawn with machine guns. One of the trickier things is trying to get a live specimen of every alien, so you can develop an effective toxic to use against them. Stunning most aliens is relativly easy, but trying to get a live Popper or Brainsucker is going to require alot of planning or alot of luck.
You can rename your agents. This makes the death of one of your agents a bit more substantial. I dunno about you, but when I see "(insert girlfriend's/wife's/familys pet's name here) has died." I get a desire to reload the game. Actually, I reloaded every time someone died. I'm just too caring.
There are three types of people you can hire as agents. You've got the normal humans who are usually lacking in skills at the start but get better as the game goes along, those alien/human hybrids from the last game (their name escapes me) who are really slow and pretty bad at combat, but have good psi abilities, and andriods, who are good at everything, and immune to psi attacks from the start, but can't ever get better. Because everyone has different abilities that change as the game progresses, you have to carefully decide who should get what type of weapon. You can't just randomly give people things...a person who has poor aim is going to be worthless with a sniper rifle, and if you weigh down a weak person they'll slow down the entire squad. This is strategy.
Explosions! You can blow up EVERYTHING if you're so inclined. Although this might make some factions in the city unhappy, it will surely satisfy you, and that's what it's all about.
The BadThe Civilians! Bleh! What were they thinking? They add nothing to the game, only serving to get in your way, and make you wait (during turn based play) for them to move during their turn. I'd rather not spend time watching helpless civilians dash around doing nothing. They don't even try to help. Maybe if they occasionally picked up a weapon to help you, or jumped up and down on a brainsucker, or something, rather then just wasting my time. Their pathfinding is pretty bad too, causing them to get stuck on steps (always in your way), and invariably I ended up shooting half of them so I could get where I needed to be.
Sometimes the map would be awfully big for the amount of aliens on it. There have been times when I've killed a total of three aliens on a map that could have easily taken fifteen. Taking seven to ten turns to carefully walk across three-quarters of a map, making sure an alien doesn't jump out and suck someone's brains out, only to find a Spitter and two eggs at the far end can put a kink in the entertainment.
After a while, before you get to take the fight to the aliens, the buildings all start to look the same. They are made of blocks, instead of randomly generated, and because of this you get to know where everything is, and even where aliens are likely to be. After seeing the same shopping mall six times it kinda loses the cool factor.
You don't get enough control over your vehicles. All you can really do when you spot an alien craft is send your stuff after it, and then just sit back and hope it gets shot down before it beams aliens down to a building, or before it destroys all your craft.
The Bottom LineAll gripes aside, this is a really fun game, even more so now that you could probably get it for $10. If you like turn based strategy games at all, go buy this game. If you like realtime strategy games, I'd imagine you'd like this game too.