I've gotta say, Evolve has nailed the designs of its hunters, the monster-fighting foursome that cooperates to kill a player-controlled beast. After our earlier cracks at the game I wasn't confident that, say, one support class character would differ much from another, but my second hands-on with the game introduced me to Bucket, a butler-voiced robot who can remove his head for use as a manually-controlled UAV. Guiding the UAV in first-person, you try to find and then zero-in on the monster for a few seconds to create a lock, granting your team UI visibility of the monster until the UAV is destroyed.
Bucket can also drop floating sentry turrets, cloak himself and teammates with an AOE invisibility ability, and he carries a guided rocket launcher. This is in contrast to the other support character we know about, Hank, who (in addition to having a normal, non-detaching head) calls down a massive airstrike as his special ability, carries a laser cutter as his primary gun, and whose main utility is granting temporary invulnerability to allies with a ranged shield projector.
More encouraging asymmetry: the new trapper class character I played was accompanied by a pet beast, a four-legged “trapjaw” alien named Daisy that essentially acts as a bloodhound, guiding the trapper toward the monster. It also revives teammates autonomously; in the round I played (and won) as the only monster yet revealed for Evolve, the Goliath, I had to put Daisy down even after incapping all of the Hunters. Even the new medic heals differently, trading the healing tether we saw from the other medic for a Lazarus Device, a device that can't heal “upright” targets and singularly specializes in bringing dead or incapped teammates back up to full health quickly. It's essentially a defibrillator; Turtle Rock admitted to me that they're still figuring out how to balance this style of medic.
One of Evolve's big promises is replayability, and this level of difference between characters in the same class encourages me that Turtle Rock could actually deliver. I don't think it was a bad decision to make Left 4 Dead's survivors completely symmetrical, but it's certainly not something that contributed to replayability. Likewise, L4D's special infected were intentionally designed as one-trick/click ponies with single abilities. Giving them a suite of abilities in addition to their single tongue pull, charge, or zombie-aggroing vomit attack would've made them less distinct threats, but controlling the special infected was also often a tedious act of positioning, waiting for the right time to strike, hoping your one attempt connected and either dying or waiting for a long cooldown to try again.
Playing as the monster in Evolve has a completely different dynamic. If it wasn't already clear, you're the prey: the players are hunters, not survivors. The moment I entered the map as the Goliath (about 15 seconds before the hunters do so in the same spot), I was running and leaping as fast as I could, trying to find packs of NPC animals to gobble so I could level up, looking over my shoulder with paranoia every few moments.
And when I did attack, it felt a bit like a L4D Tank encounter taken to its mechanical extreme: the Goliath breathes fire, it has an area-targeting pounce attack, it has a rock throw and a charge ability, all bound to separate keys. Each of these abilities level separately as you evolve your monster. I liked the armor/health mechanic for the monster, too: any health damage is permanent, but armor can be restored by eating creatures in the environment, an action that carries its own risk.
An open question with Evolve, though, is whether its open, arena-style maps, swappable characters and monsters will birth a handful of highly-successful strategies that later have to be nerfed or patched out of the game. This was the case in Left 4 Dead, where stuff like melee and closets had to be re-balanced after players discovered them as a tactic of least resistance.
The slow trickle of information Evolve's fall launch is one of two worries I have about the game. I've only played two of the game's “more than 12” maps and have no idea what the other (“multiple,” I'm told) monsters look or play like. My hope is that Evolve's roster of beasts resembles a kaiju-like spectrum of monsters with different locomotion, playing styles and combat mechanics, but we really have no idea whether or not that's the case. There's also no official word at this time on whether Evolve will be moddable. Considering 2K's fondness for releasing DLC for some of its franchises (namely Borderlands 2 , for which 46 separate things can be purchased), and Evolve's modular nature, I'd bet my favorite hand that 2K will sell some combination of new weapons, maps, hunters, or monsters.
Evolve has demoed terrifically, but with so much of the game's focus being on variety and replayability it's concerning that 2K and Turtle Rock aren't close to filling in the whole picture this soon before launch.