The tower defense genre hit its peak somewhere in the late Aughts with Plants vs. Zombies, Desktop Tower Defense, and PixelJunk Monsters defining and dominating the genre. It's stagnated a bit since, due in large part to how rigid the genre's rules are. The last few years have seen a resurgence, but not in the traditional isometric-viewpoint-sense of games passed. Watching with bated breath if your best laid plans match the opposition making its way toward your goal line still has its charms, but what if you were the opposition? That's where the Anomaly series comes in.

Anomaly 2's motif may be transformation, but the core of what made its 2011 prequel so refreshing remains largely unchanged. Running a tiny commander around a maze of city streets and dropping power-ups and buffs to my units hurling explosives at adversarial towers felt great in the first game, so it's still in the sequel. The dialog and story remain just as cheesy and cliché, with one story line being, wait for it, find the German scientist working on a super-weapon that will turn the tide of battle against the alien occupiers. It's campy, but Anomaly never took itself all that seriously to begin with so it still works. I can only hope an alien occupation would be this cheerful if it actually happened.

The areas I played took place in a frozen version of North America, featuring a bevy of icy sights and even the Statute of Liberty almost completely submerged in a frozen Upper New York Bay. Anomaly 2's frigid wastes are a stark and welcome contrast from the oppressive earth tones of its predecessor: metallic tentacles and veins weave through the Rocky Mountains, exposed sections flashing red against the azure nighttime snow and ruined freighters rest permanently docked in the streets of Manhattan. Everything feels appropriately cold and destroyed in the several years following our first encounter with the insect-like polished aluminum nemeses ; all the better to weave a squad of xenophobic badasses through. Mission structure varies from short and snappy “destroy X targets” affairs to lengthier, much more tactical exfiltration and rescues that can take upwards of an hour to finish. Some missions have optional and primary objectives; there's as much or as little for the taking as you want.

Where Anomaly deviates furthest from the formula, though, is in the ability to swap between two forms of each unit almost whenever you see fit. The Assault Hound goes from a treaded twin-chain-gun turret whose damage and rate of fire increases with sustained firing to a Hell Hound, a lumbering dual-napalm-cannon bipedal mech whose firing arc is powerful but very narrow, after a double click of the mouse. Each form has its own tactical strengths and weaknesses. As a general rule, the mechs have less attack range but are considerably stronger armor-wise and have more powerful weapons. Hell Hounds make great lead units because they can take a hit, allowing the weaker but heavier-hitting Sledge Hammer, or its mech form, Rocket Hammer unit's artillery to do its job from a safe distance. At first, all this is just window dressing. The introductory mission had me switching back and forth between forms to get comfortable with the mechanic, but soon after the added depth switching forms affords began to show.

Morphing between mech and standard forms is an absolute necessity in order to succeed in Anomaly 2, perhaps even more so than proper unit placement in the prequel was. Using the wrong unit and form in the wrong position against the enemy Charger tower, for instance, has dire consequences. The Charger absorbs gunfire when it's attacked by a unit with too high a rate of fire and too low of damage per shot, transforming into a Storm Reaper, like an Assault Hound. The Storm Reaper's a nasty four-tentacled monstrosity capable of wiping out an entire squad with a few of its lightning-based attacks; It's bigger, faster, and more heavily armored than its base form. Attacking with the cheaper and more powerful Rocket Hammer prevents this from ever happening, though.

Beating the odds with a limited troop budget and overwhelming amounts of enemies requires precision and patience. Anomaly 2 stopped holding my hand at the third real mission and threw me into a sub-zero lion's den. Manhattan's grid of streets and destroyed skyscrapers holds all manner of nasties just waiting to send me back to the last well-placed checkpoint. My first encounter with a Scorcher tower was relatively simple: I placed a decoy, distracting the flame-spewer's unidirectional attack so I could hit its weak point from behind.

The next unit I encountered had learned to shoot in two directions at once. Clever girl. I thought I'd be able to subvert its primary tactic by circumnavigating the block, coming up alongside and attacking while its attention was elsewhere. Timing is key as the decoy lasts less than 10 seconds. Troops move at a fixed pace. I had to keep everyone repaired. I had to keep my diminutive avatar safe. I had to dart in and out of harm's way laying down the scant few decoys amidst the fracas. In the end, I defeated the gasoline-breathing nightmare, but the T-shaped intersection and firing pattern left my two-unit squad halved and out of repair power-ups. And there were at least two dozen more intersections between me and mission's end. I gritted my teeth and reloaded to the last checkpoint. Next time.

Early builds tend to have a few glitches or rough edges here or there, but they were largely absent here. One glitch I encountered forced me to restart a short mission after the rest of my objectives were cleared because circling back to destroy a few enemies I'd avoided triggered a mission failure. What I've seen of the game so far already feels incredibly polished and ready for release in the next few months. Anomaly 2 is showing a lot of promise.