Everything was going to plan in X-Morph: Defense until a giant mech started stomping its way through the city, carving a path towards my newly planted alien base with vengeance on its mind. Suddenly, the defensive towers I'd placed to shoot human tanks and trucks were useless—this hulking mech was just stepping on them, crushing my puny defenses underfoot while my alien master warned me of its progress.

So I did the only thing I could think of. I dropped a building on it.

Hell yeeeeeeea—oh that didn't do anything. The mech shrugged off the falling skyscraper debris and responded by blasting me with a giant laser cannon. Fair enough. It is a giant mech that walks through buildings, after all.

Still, I'm enamored with X-Morph's physics-driven environmental destruction, something I've never seen in a tower defense game before. My plan to topple a skyscraper onto a giant walking tank may not have worked exactly as planned, but destruction has a point in X-Morph. Knocking a big enough building into the mech's path changes its route to my core, giving me time to plant more towers and figure out how to take it down. It's a classic tower defense strategy, made flashier with physics and scale.

X-Morph's penchant for destruction also makes for some tricky but interesting strategic decisions. I could place towers and link them with laser fences to block off a path and change the enemy route through the map. But what if I knocked down a building instead? That's a one-time decision: if I change my mind I can clear out the debris, but the building's gone. Still, this way I can also set a new path and keep my towers in the heat of the action. In the opening three levels, which I've gotten to play in a demo build, I spent more than a few minutes examining the map between waves to figure out how best to place my towers.

That's partially because X-Morph throws more enemy paths at you than I've experienced in any other tower defense game, and it does so from the second level. It keeps adding new routes mid-mission, expanding the playing field of a map outwards in all directions. Think you have the northern half of the map built out into a suitable maze? Surprise! Two new paths just opened up from the south.

The only reason this isn't totally unfair, and is actually possible to deal with, is because X-Morph is as much a top-down shooter as it is a strategic tower defense game. You control a ship, with a rapid fire laser cannon and a powerful charge shot that doubles as a shield. Using those weapons to fend off enemy units is vital, because there's no way your towers can handle them all.

Like most top-down shooters, this side of the action is a bit mindless but feels good. The X-Morph ship glides quickly around the map and nailing an entire line of tanks with a level three charge shot feels is especially satisfying. And these weapons are just the beginning—X-Morph has a pretty extensive skill tree for both ship power-ups and towers. Take the Dark Matter Bomb, for example, an upgrade X-Morph suggests for the second mission. This thing can instantly cut a building in half, which is perfect for reshaping the map.

After the first three missions of X-Morph I've only unlocked one tower upgrade, an anti-aircraft gun, so there's plenty of strategic depth here I've yet to touch. So far, X-Morph's missions feel on the long side for a tower defense game, especially starting out. I enjoy methodically building my maze and then dealing with a few escalating waves of baddies before moving onto a new map, but even X-Morph's early missions stretch beyond half an hour. 

I'm also not sold on the way X-Morph's second and third mission add so many extra routes for enemies to pour in through as they go on. On the one hand, this keeps me on my toes and keeps the action frenetic. That's good. But I feel like it also somewhat misses the point of the tower defense genre—that satisfaction of optimizing your maze, then watching the enemy waves crumble before your perfect strategy. X-Morph is less interested in letting you optimize, and more interested in escalation.

But that's just what I find satisfying in tower defense, and I've never played one that escalated with giant mech bosses, destructible skyscrapers and massive bombers that will sweep across the map destroying your towers. What I've seen so far makes me eager to play with the rest of X-Morph's skill tree, especially in co-op. Little-known tower defense game Tower Wars was, for awhile, one of my favorite co-op experiences, and I played even more of FPS-tower defense hybrid Sanctum 2. I think X-Morph has the potential to scratch that same itch.