Enemy Mind is a nifty creative twist on the side-scrolling shooter genre. Instead of controlling your own ship, you play as a psychic entity that can commandeer an enemy ship at will. Just press the button and you can swap into a different ship. It's a simple enough premise, and the game executes on it pretty well--well enough that it feels like a key piece of the gameplay rather than a gimmick.
Each ship has limited ammo, see, so you're forced to jump from ship to ship in order to keep fighting. Levels are designed to nudge you toward playing a wide variety of ships--when you run out of ammo, you won't always be able to hop right into a new copy of the same ship. And the boss fights of each level are built around the mechanic--for example, you might have to jump around a circle of stationary turrets to reach the boss's rotating weak point.
The story is interesting. It's not you against Bad Guy Aliens. You're dropped into the middle of a war between aliens and humans. (You'll get a different ending depending on which side's ships you use more frequently.) The two factions are, visually, very distinct, and when they're onscreen together they'll actually fight each other. Furthermore, both sides quickly become aware of your presence, and you get to hear them reacting to how you're taking over their minds, which is pretty cool.
So I like what they did, generally. That being said, there are some flaws. For one, it would be nice to have more variety in the ships. There are a decent amount to choose from, but a lot of them are just variations on "shoot forward in a straight line." Oh, and another thing, it's always forward. You can't turn around. This is definitely problematic, because the enemies CAN turn around, and they WILL come at you from both sides, and you'll just be, like, well, I can't turn around and shoot the guys behind me, so...bleh. Also, you supposedly have a limited numer of extra lives, but in practice, you get unlimited continues, and continuing puts you at the exact same place as respawning, so...what's the point of having lives, exactly?
In any case, it's a short game--I'm not very good at shooters and I beat it in 3 hours--so it doesn't wear out its welcome. You don't need to invest much time to enjoy this game. I don't know if it's worth $10, but if you have it in your backlog from some bundle or other, I definitely recommend giving it a look, just because it's interesting and it does something new and unique. It's short, it's sweet, and while it's not the best shooter you've ever played, you've probably never played another shooter like it.
P.S. Make sure to check out the Rock Simulator in the Extras section. It is glorious.