Fun Fast Paced Shooter Masher Action.
As I stated, this game was very difficult (at least for me) on the computer, but I think having a controller to play it with gives it a much better feel. That B button (on GC, not PS2 obviously) will become your best friend in this game as it is used to fire your gun.
You have a basic gun that has unlimited shots so you can shoot as fast as you can mash that button, but you'll also get "upgrades" throughout the game each with their own style of shots. Some that freeze enemies, set enemies on fire, shoot acid at enemies, etc. However, these have limited numbers of shots so you can't use them forever. You'll also have a knife that you will automatically use if you are close enough to an enemy along with grenades that you can throw to do bigger damage...watch you don't blow yourself up though of course.
The gameplay is simple side-scrolling shooting. You go from left to right (sometimes some up and down) and you shoot everyone and everything that gets in your way. As I said, the B button will become your best friend. Enemies take a few shots a piece to kill with the basic gun, some special weapons will only require one shot for a kill. You'll also fight bosses at the end of almost every level, some levels you'll fight one in the middle and the end.
Bosses are big and fairly creative. They'll require at least somewhat of a strategy to defeat. At the least some mad mashing and dashing.
The game is probably about 6 hours long the first time through. It can be completely in a good sitting. After that I've cut the time it takes to beat it in half. Although this may be a short time for a standard action game to last, rest assured, your hand will thank you when the game ends. You'll be plenty satisfied with the amount of Hominid in this game.
The downside to the game (in my opinion) was the flying style missions. They weren't dreadful by any means, but they weren't my favorite part of the game either. They were that "meh" part. Overall though it didn't harm the gameplay.
On top of the normal mode is a "PDA" mode in which you can play some fun little platform/puzzle type games with Hominid on his PDA. You can also create your own levels in this.
The main game also supports multiplayer which can be fun and you can customize your character with a handful of different hats so you can tell yours and your friends apart. Some of the hats are hilariously awesome.
There's no doubt that you'll have a good time if you pick up Alien Hominid. It's fun simple action that you can just pick up and truck through a few levels or even the whole game. Some points may be a bit frustrating at times, but its never overwhelmingly difficult. Enjoy.