As thrilling as the shooting can be, and as much depth and variety as there is to the action, the gameplay has one notable flaw. Specifically, the core mission designs simply aren't up to par with everything else. It's not that they're bad, so much as they are very linear and generic. It's a lot of get from point A to point B scenarios, basic escort missions, and gameplay of that ilk. The basic level designs are good, but it's usually overly clear where you need to go at all times, to the point where exploration is largely unnecessary. The only times you might be confused are when you mistake a section of the scenery for an obstacle, when it's actually the path to the next area.
Not only can you issue tactical commands to computer-controlled allies, they'll actually execute them with little hassle.
All told, the single-player campaign is very enjoyable, though also rather short and devoid of a decent conclusion. If you're good, you can get all the way through in about four hours (though in real time, it'll probably be more like twice that with the amount of postdeath restarts you'll have to do). But the campaign is good enough to play through multiple times, especially if you've got a friend nearby to play it with you. Every time you complete a mission in the single-player, that mission unlocks for the cooperative mode. Co-op play isn't too terribly different from the single-player experience. The game doesn't try to ramp up the difficulty by throwing more enemies at you, though it also doesn't give you more ammo pickups, meaning you'll have to be more careful not to waste it. Still, everything's more fun with a friend, and being able to go through the whole campaign cooperatively is a nice bonus.
Additional modes include a single-player challenge mode, as well as competitive ad hoc multiplayer. The challenge mode unlocks a series of challenges each time you complete one of the campaign's chapters. Objectives such as basic target shooting and timed demolition missions are the norm here. These are decently fun on their own, but by completing and scoring high on these missions, you can earn points that go toward character upgrades in the campaign. During the initial screen where you pick your weapons, you can choose up to three of the unlocked upgrades to take into battle with you. Increased health, additional grenade slots, and unlimited ammo bonuses are just some of the available options. What's especially cool about this is that different missions require different abilities, so being able to change up which upgrades you use from mission to mission is extremely helpful.
The competitive multiplayer should be the best aspect about this game, but it's unfortunately limited at the moment. There are four play types: deathmatch, team deathmatch, assault, and capture the flag. For anyone who has been playing multiplayer shooters over the last decade or so, these modes should be pretty straightforward. Functionally, the action is identical in multiplayer as it is in single-player, with the same weapons, same targeting functions, and same strategies. It's designed for up to six players to play at once, and you'll pretty much need as many people as possible to make the game fun. Playing multiplayer with just one or two people isn't that exciting, since the maps are a little too large for such a small number of players. However, what's really unfortunate about the multiplayer is that it isn't online. The game only supports ad hoc play, and the game-sharing option doesn't offer more than a couple of single-player demos. There is a download option that will allow you to get new content for the game, though the specifics and availability of that content haven't been announced. According to the game's developer, there will be more maps to go along with the six included with the game, as well as a downloadable patch that will add infrastructure multiplayer to the game.
Liberation's presentation might not look like much at first, with its zoomed-out camera view and seemingly drab setting, but as you get into the action, it warms up on you very quickly. The character models and animations are top-notch. The simple act of watching characters run around and shoot is pleasing enough, but watching them fly through the air after getting blown away by a big explosion is immensely entertaining. The game uses rag-doll physics with good effect. Occasionally, you'll see bodies clip through areas they shouldn't, but this is one of those rare cases where the rag doll looks less ridiculous and more realistic. All throughout the game, the frame rate holds up, too. Particularly huge explosions tend to make it drop a bit, but generally, the game runs totally smooth.
The game's audio is also very impressive. The soundtrack consists of the typical military march score that you'd expect, and it's actually a bit repetitive, but the sound effects are fantastic compared to what you normally find on the PSP. Guns sound great, and explosions sound even better. There's also some solid voice work from the supporting players. Mostly it's just Helghast soldiers screaming orders at each other, or just screaming due to imminent death, but the dialogue from your human cohorts is very good, as well. The only one that's a bit off is Rico. Seriously, how many times can you shout, "Eat lead, a******!" before the words lose all meaning?
While the single-player campaign is ultimately too short and devoid of story, and the multiplayer suffers from the lack of infrastructure play, Killzone: Liberation is still an excellent and engaging shooter. Its tightly woven shooting mechanics and tough enemy opponents create some of the most intense battles you'll find in any game on the PSP, and its great presentation and duo of multiplayer modes give it plenty of longevity. Some people might be put off by the difficulty and the brevity of the game, but most will find a thoroughly unique and enjoyable experience in Killzone: Liberation.