Killzone: Mercenary doesn't have to do much in order to be the best first person shooter on Vita. The bar has been set so low with Resistance: Burning Skies and Call of Duty: Black Ops Declassified that merely being competent would make Mercenary best-of-class on Sony's struggling handheld.
Well, Guerrilla Games has gone above and beyond that bar. Killzone: Mercenary is absolutely gorgeous and is arguably the best-looking game on Vita so far. It's also pretty fun.
It is unquestionable that Mercenary's biggest selling point is its graphics. The Killzone games have always been lookers on PS3, and it's amazing how much of that experience has been translated onto the Vita. Guerrilla says it's the same engine from the PS3, including all the visual tricks you'd expect from a home console game: HDR, dynamic lights, volumetric fog, etc. It's not quite a PS3, though. Character models obviously use less polygons, and there are fewer enemies on screen at any given time. While it may make the battlefield seem less hectic and chaotic than in Killzone 2 and 3, it's nonetheless very impressive.
Another selling point of Mercenary: it actually has a campaign mode. Guerrilla promises it will be about an 8-10 hour single player adventure, one with a continuous narrative that goes through some of the big moments in the Killzone universe, such as the liberation of Vekta and the invasion of Helghan. While the title suggests a disjointed series of replayable missions a la Black Ops Declassified and Unit 13, I was told that Killzone is not quite like that. In fact, in one of the levels I played, I was escorting a child--suggesting that key NPCs will make the story progress in meaningful ways.
Of course, it wouldn't be a Killzone game if it didn't have online multiplayer. Mercenary's offering isn't quite as robust as the console game, limited to 4v4 matches across six maps and three modes. One of the returning modes is Warzone, which has teams going after alternating objectives over five rounds. This proved to be a fan-favorite on PS3, but will it be as fun when only four players can be on each team?
Vita's dual analog sticks are put to good use, and I found it rather easy to jump into the game. However, there was one quirk: running and crouching are both mapped to circle, and I often found myself crouching when I wanted to sprint and sprinting when I wanted to crouch. There's definitely a learning curve here, but I'm sure there could've been a more elegant solution (perhaps using the rear touch for one of those functions?).
Thankfully, Mercenary doesn't rely too heavily on gimmicks like most Vita-exclusive games do. The touch screen is used, but quite sparingly. When meleeing enemies, you'll have to swipe the screen based on an arrow that appears. I actually quite like this addition, as it no longer guarantees a kill when you're near other enemies. If you're too slow (or swipe incorrectly), you're left vulnerable. Some of the gadgets from your "Van-Guard" may also take advantage of the hardware--but these don't seem to distract from the core gameplay. These tools, which recharge as you kill more enemies, are reminiscent of the remote drones you control in Black Ops 2. One particular one I used let me fly around, lock onto enemies, and claw at their skulls (ouch!).
One concern I have about Mercenary is that each level might be too long. Unlike Vita's other FPS games, these are not "bite-sized" missions at all. Given how lengthy they are, it's a good thing that Vita has such an excellent sleep mode. There are some concessions made to increase replayability. For example, once you complete a mission, you'll unlock "special contracts" that will have you performing specific actions during replays. You can also go for a higher score. Every action, every kill earns you cash--and cooler kills (like stealth takedowns and headshots) give you a lot more money. Stylish play will help you earn more money and unlock better gear faster. Best of all, money earned in single and multiplayer will go to the same pool.
The brief time I've spent with Killzone: Mercenary is, for better and for worse, a more robust experience than any other FPS I've played on Vita so far. Given the dearth of software on Sony's handheld, many are likely to settle for whatever they can get their hands on. However, Guerrilla Games' next has the potential to be much more than adequate-enough--it could even be great.