I knew nothing about Shadow Complex leading up to the game's release, but after hearing a few friends hype it up and watching a few videos I purchased it right after it's release. While the game is a bit short (if you really push it you can beat it in 2 hours or so) it is still a ton of fun, worth a purchase.
Tracing it's roots back to "Metroidvania," Shadow Complex is a 2.5D side scrolling platformer/adventure game. Controls are a bit odd as one stick moves your character and the other aims your gun, but after playing for a little while it becomes second nature. You start off as a mere mortal and throughout the game acquire power-ups that turn you into an unstoppable behemoth (to the point where at the end of the game, if you've picked up all the items you are neigh invincible). You've got a few guns to acquire, different launchers (rockets, grenade, riot foam which is fantastically fun), health/armor upgrades and suit upgrades. Suit upgrades give you new skills and let you access new areas.
You will be hard pressed to find a negative review of the game from any of the major gaming publications/sites because, quite simply, there are very few areas to fault the game on. The story is decent, the gameplay is a ton of fun, the graphics and sound are excellent, and it has a very clearly defined gameplay style that it stays within and plays well in.
If you're a fan of the old 2D Metroid games or Castlevania: Symphony of the Night you are going to absolutely love this game from start to finish, through your multiple playthroughs. If you just like well made fun to play games you'll enjoy the game equally. Give Shadow Complex a whirl. At $15, it is definitely worth the price!!