Combining the visual presence of flOw with a few casual real-time strategy and shooting elements, Deep is an intriguing hybrid game that's friendly to a variety of playing styles. You control a single cell-like critter who can move and shoot in any direction, but you're also in charge of a thriving colony of warriors who want nothing more than to eliminate the enemy. Play it like a shooter, play it like a strategy game, or play it like a little bit of both. Either way, it's an interesting dive under the sea.
Your goal in Deep is simple: make all the enemy base belong to you (see what I did there?). Bases are amoeba-like critters with a single dot of color in their center denoting which team owns them: purple for you, red for not you. Bases periodically spawn allies and are fitted with cannons at the end of each tentacle. Take out the cannons and a base is yours, but be careful, as those red guys are out to nab your bases and will do so with vigor.
Swim around with the [WASD] or [arrow] keys and fire with the mouse. Whenever you defeat an enemy, tiny "stars" will appear that refill your health. And trust me, you'll need the boost, as both ally and enemy fire looks identical, and when you're in a swarm, it's tough to know where to dodge.
While floating around and shooting stuff could be fun in its own right, Deep adds a layer of tactical strategy with one simple command: tap the [spacebar] to summon free-floating troops to follow your lead. Take the soldiers to an enemy base to make quick work of its cannons and claim it as your own. Doing so leaves your other territories vulnerable, though, so it's a bit of a trade-off. Most of the time I went out on solo strike missions to take over enemy bases, then swam around defending it from attack until a few of my own warriors spawned. What can I say, I have a bit of a hero complex.
Each of the game's 15 stages takes place deeper and deeper in the ocean, sending you down to face bigger, more difficult foes. The levels aren't all that different from one another, and even though the enemies get tougher, so do you and your allies. After each level you get to spend points upgrading your main craft, adding buffed health, stronger weapons, faster reload times, etc.
What makes Deep so interesting is its reliance upon a combination of shooting skills, strategic planning, and plain old luck to win. The levels could use some more variety, and it would be nice if you could tell enemy and allied fire apart, but otherwise, it's a great experience that doesn't require you to be a shmup expert or a real-time strategy fan to enjoy.