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.

Screw whatever anyone says about this game. Most people only hate this game cause they played 30 minutes and assumed that the game's never picking up, or just know it's a 3rd person shooter of a beloved strategy game, which means it'll automatically be bad. Enforcer is far from that.
You haven't lived till you've gone mach 5 around a mall, launching grenades everywhere in a fountain of death, obliterating all in your path. There are countless weapons and powerups in this game to please you (do not unlock the freeze gun), and the upgrade system allows you to improve just what you want. This upgrade system is key to the game, as it's what turns a rather simple character into the super sonic, destructive Enforcer he should be. The main objective of about every level is "Murder Every Alien", and that's all you need really. Beautiful death and carnage for the sake of it.
The levels are generally very open and allow for exploration, which will let you unlock bonus levels and get more points and more upgrades. But they never feel mandatory, so you're free to just kill to your heart's content. The game allows you to check at any time where the next enemy spawner is, so that you can go there to kill things without having to get lost, allowing the flow of the killing to proceed unhindered.
The game does suffer from some flaws, as any will. If you take too long to go to an objective, your scientist ally will persistently annoy you to continue onwards. A few of the guns, such as the aforementioned freeze gun, will be useless and since the only way to get rid of a gun you're carrying is to use up your ammo or find a different one, it can create a problem at times.
Beyond those, the rest are insignificant upon this beautiful creation. The game isn't really complex or as deep as its predecessors, but it doesn't have to be. The game succeeded in being a well-made, over the top, insane shooter, and it succeeds well.

Do you like Gauntlet? Do you have a soft spot for the impressionistic nature of the simple geography and low resolution textures of c. 2000 Unreal and Quake maps? Does finding letters inside of colorful balls bring back good memories of Bubble Bobble?
This is pretty playabe with a gamepad too if you remember your UT console commands from 15 years ago. Type "preferences" in the console and you'll be tapping A to bound from roof to roof of boxy trailer homes in search of the next alien spawning thingy in no time.

Oh god it's so bad I can't stop playing...

A clunky old over-the-shoulder shooter that is way past its prime. And I'm not sure it was that good back in the day either. Really simplistic: run around, shoot aliens, pick up health and armor, etc., but not very deep.