So i got Alien Syndrome about 5 hours ago and had about 4 hours of playtime (had to eat, you know). I haven't gotten far in the game but I feel I have played enough to give it a review.
Controls: You move with your nunchuck and move the camera by tilting your nunchuck. You shoot with either A or B and aim by pointing on your screen. You have health and energy packs which you can activate by pressing left or right on the D pad. The nunchuck movement is just like Ultimate Alliance. It's sucky at times but most of the time it's find and pretty easy. Shooting is a breeze and you can bind two weapons to your buttons, one to A and one to B. Down on your dpad switches between melee and gun. Melee is pretty cool. Regular b attack is a lunge forward. You can swing and all, wave your wiimote around and do different attacks.
4/5 - Simple, pick up and play controls.
Gameplay: Ammo is limited and you either pick it up or buy it from the scarab. There's money that drops and a weight system (think encumbered). When you level up, you get points to put into attributes and abilities. Abilities lets you use new weapons, there's only 4 categories though. The game is really fun. You run around getting to this orange dot on the map and kill aliens on the way. That's what you basically do.
3/5 - It's just killing aliens, what more could you want!
Graphics: graphics aren't that great but they don't suck either. If you want a game to have amazing graphics or up to the Wii's potential, don't expect it. The graphics are decent. Weapons have cool effects and the aliens look really cool.
3/5 - Average, not amazing but good enough and ignorable.
Sound: I'm no expert at sound, but the sounds were really cool. Weapon sound effects were really cool, aliens sounds were really cool. There wasn't really any sounds that stood out as bad but didn't surprise me though. The game music was so-so though, I didn't expect Zelda like orchestra music anyways.
2/5 - average, nothing special
Multiplayer: They only have Co-op, i knew this already. Single player might be fun for some but co-op makes it even funner. I've played with 3 other people and it's been a blast. There's not really any competition like you get in deathmatch, more of a team effort. The only problem is that you must keep track of who's who and remember your color. I sometimes forgot where i was and was trying to kill someone until 5 minutes later i realized there was a wall in the way, wasting all my ammo.
Overall: This game is pretty good. You run around killing aliens. This game isn't a must-have but isn't something that should go into the bargain bin. I'd don't know who to recommend this game to, so I'd say rent it if you're not sure. I am certainly enjoying this game. I would like to reiterate, this game is not one of those must-haves. If you have the extra money and curious, I would highly recommend it. Otherwise, i'd save it for Mario Strikers Charged.
Overall: 3/5 - good game, but not perfect nor the best.