First of all, X-COM: Enforcer has almost nothing to do with the X-COM series aside from reusing some enemy designs and backgrounds, and even that connection is tenuous at best. So forget all notions of turn-based strategy and base building and all that. This is a simple run and gun TPS.
You run through loosely divided sections killing absolutely everything you come across -- in this case, enemies that spawn from generators. You only wield one weapon at a time and can pick up others as they spawn in the level (and they respawn after a while). Killing enemies makes them drop points (literally) which you gather and can trade in for upgrades to your weapons, health, speed etcetera. It's all kept as mindless as possible -- run around for too long without direction and you get a gentle reminder of where you're supposed to go, in the form of a big blue blinking arrow over your head, so that, in theory, even the biggest idiot can find his way around. Even so, I managed to get stuck at level 3, where you're supposed to go up somewhere but I could find no way of getting there -- the game has no mini-map or mouselook. Whether that says something about the game or me, I wouldn't care to say.
It reminded me a little of Painkiller (there's even a weapon that shoots blades), except that Painkiller has more variety, better graphics and higher difficulty. This game is by no means a classic, but as far as mindless fun goes it does what it sets out to do. I'm giving it a vague "not recommended" based on just the half hour of play I had with it. I can't really recommend buying it on its own, but as long as you don't go in expecting strategy, it's an inoffensive addition to the X-COM Complete Pack.