Unlike other Killzone games, Liberation is a third person shooter. The player sees the action from an isometric angle, allowing a better view of enemies before engaging them. The camera will float towards the nearest enemy, even ones that are off-screen.
Players can press R to duck for cover, and press Square to shoot from cover. While in cover a player can press L to target objects such as explosive barrels or crates. Players can do a dodge roll by double tapping L, which will get them quickly away from explosives, or cause explosive tipped darts to fall off.
In some missions players can command a teammate. They can have the computer assisted character follow them, stay at a location on the map, or have them preform map specific tasks like climb a wall with a grapple, knock down a wall, or plant explosives. When the computer based ally’s health drops below zero the player must get them a syringe within 20 seconds. They can be given a syringe anytime their health is below 50%.
Weapons, ammo, explosives, health and syringes can be found throughout the map at supply depots. Each supply depot will have a limited amount of supplies. If a player changes weapons, their previous weapon will be added to the supply depot. If the weapon is already there then the ammo is added to the total ammo for that weapon. Health packs and ammo can also be located from dead enemies and in destroyed crates.
The original disc version of the game comes with 16 single player missions. The missions are divided up into four chapters each with four missions. These range from ground troop based combat missions to finding vehicles and using them to traverse the terrain, or co-op missions with a computer based ally. At some points players may be asked to defend a location, or flee from attackers. Update 1.2 for the game includes an extra chapter with four missions. While the story is concluded with the first 16 missions, these four missions act as a prologue for Killzone 2.
After each chapter is completed then six challenge games are unlocked. These games range from target practice to killing as many enemies without dying, to going through a level and planting three C4 charges as fast as possible. These games have three different goals for completion. These are bronze, silver and gold. Completion is worth points, which are required to unlock new abilities. Gold completion is worth 20 points, silver worth 15 and bronze worth 10.
When the game launched player vs. player combat was only available in Ad-Hoc mode. Update 1.2 included online play through infrastructure mode. The two modes are exactly the same except infrastructure mode includes community features. This includes a friends list, a messaging system, and the ability to invite friends to the lobby. In game communication includes a menu based command system and use of the PSP microphone. Members of the winning team receive 20 points. A kill is worth two points, and a suicide is negative one point. Team based objectives such as picking up the flag or planting C4 are also worth points. All game modes support eight players except for death match duel.
Co-op can only be played between two PSPs locally. It goes through the same campaign as the single player.
Players start at opposite ends of the map and must bring the opposing team flag to theirs. If a teams flag is dropped a team member can return it by touching it. Both flags are visible on the radar at all times. The Radar is accessed by pressing Select, and accessing it prevents a player from moving or engaging in conflict. The game ends when either team has captured the others flag three times, or when time runs out.
The ISA must defend a communication beacon, while the Helghast must plant three C4 charges near it. The match ends when either the beacon is destroyed, signifying a Helghast win, or when time runs out, signifying an ISA win. Players who are planting C4 will automatically stop when they are shot or damaged. Smoke grenades which are used to prevent players from being targeted are commonly used around the communication beacon. Remote detonated mines are also commonly used. Players can still be melee attacked or hit by stray fire wile hidden in the smoke in order to stop them from planting the charge.
The objective of team death match is for players to kill the opposing teams members as much as possible. The team with the most kills at the end will win. There is no kill limit and the game will end when time runs out. Players should move as a group or camp at the better supply depots. When a supply depot runs out of syringes and health they should abandon that supply depot for another one.
In Death Match players must get as many points as they can. The player with the most kills at the end wins. The leader’s location is always given on screen, by a large trophy over his head. Even when he is off a players screen, the icon will be on the side of the screen showing which direction they are in.
Same as death match, only limited to two players. The maps are much smaller versions of the eight player maps. They are the same, except with sections blocked off with barbed wire and one map has a ladder added in one location.
There are a large number of unlockables for Killzone Liberation. Many abilities are available for the single player and co-op campaign by completing the challenge games. For most of the game the player can select three of the abilities for the missions, but if the player has completed all challenge games on the gold level, including for the downloadable content, then they can select up to five abilities.
The various weapons can be unlocked for use at the start of single player and co-op missions, and can be upgraded to a second, more advanced version. The more advanced versions have marginally higher damage levels. Both weapons and upgrades can be unlocked by collection Vektan Dollars. Vektan Dollars are located in $1000 dollar increments in suitcases hidden in crates throughout the single player campaign. There are 88 suitcases in the disc version and 12 in the downloadable content. Because of the 12 located in the downloadable content some weapons cannot be unlocked without it.
Bonus behind the scenes content is unlocked by playing through both the single player and co-op missions on various difficulty levels. This bonus content includes concept art, wallpapers, behind the scenes videos, and the game soundtrack. This content is available by signing onto Killzone.com through the Killzone.com option in the main menu in game. Since the July 23, 2008 update to Killzone.com problems have prevented the content from being accessible or considered unlocked on the users profile. Content can still be accessed through the website on the PSP, but not on a computer or other internet enabled device. Also, some content that is considered unlocked in the Stats and Rewards section of the game is not listed as unlocked on Killzone.com when accessed through the PSP.
Many different characters are unlockable for use in online play. These are unlocked by playing through the single player, co-op and online play on various difficulties. These include the single player and co-op characters, the villains from the Helghast faction, and some unnamed soldiers from the Helghast. These soldiers are named after their character class, such as grenadier, sniper and commando.
M82-G Assault Riffle
Standard issue assault riffle for the ISA. Compared to the Helghast’s standard issue assault riffle it is more accurate, but has a smaller clip. It also has a slower rate of fire.
StA-52 LAR Assault Riffle
Helghast standard issue assault riffle. Great for combat against ground units. It has a high rate of fire and large clip size.
IvP-18 Tropov Machine Pistol
Sidearm with high rate of fire. Holds 24 rounds and can empty a clip in under 1.5 seconds. Takes 24 rounds to kill a player.
StA-52 SLAR Sniper Riffle
Long range high calibre weapon. Holds one round and has a long reload time. Takes three rounds to kill a player.
M13 Semiautomatic Shotgun
Shotgun with two rounds. Does high damage. Kills most enemies in 2 rounds. Slows down the player.
High calibre side arm. Described by most veterans of online play to be the most powerful weapon in the game for troop vs. troop combat.
M1 LMG ‘Tyrant’
Light Weight version of the M224-A3 from the first Killzone but without the missile launcher ability. Only Rico Velasquez uses this weapon in the game.
Launches grenade tipped darts. Great weapon for defending a location for extended periods of time.
VNS-10B Scylla Chaingun ‘Cerberus’
A heavy gun that slows down it’s user substantially. Has unlimited ammo and a high rate of fire, but is prone to overheating.
Lays down a wall of fire to prevent players from getting through areas. Best used in creating choke points.
BLR-06 Hadra MRL
Rocket launcher that can hold up to three rockets at a time. Does 80 damage to a troop. Slows down it’s user significantly.
M194 Percussion Grenade
Standard issue fragmentation grenade for both factions.
Mine that detonates when walked on or driven over. Not available in multi player.
Remote Detonated Mine
A mine that is detonated by the player, ideally when a target is near. Effective near flags, C4 placements, and choke points.
Grenade that emits a large amount of smoke. This prevents targets in the smoke being targeted or being able to target.
Melee attack damage is based on the weight of the weapon the player is wielding. The strongest melee attack is while using a rocket launcher. This will cause 20 damage. Coupled with the 80 damage from a rocket blast a kill is guaranteed in multi player. In single player, double and triple damage melee attacks can be unlocked.
Used by the Helghast for their invasion of southern Vekta. It is used by the Helghast in many single player missions, and is used by Templar in one mission. It has a rocket launcher that can be rotated, and a stationary chaingun that fires in the direction that the tank is facing.
Used to travel through the swamps in one mission, this vehicle has a stationary rocket launcher that shoots in the direction that the hovercraft is facing, and a chaingun that that can be rotated in any direction.
Used by the Helghast air borne troopers, this weapon has unlimited ammunition and can get the user to heights not achievable by jumping. Is used to maneuver past large canyons or above large walls or hills.
An unnamed light armoured transport vehicle is used in the downloadable chapter, and has no weapons. It is used to traverse through sand dunes and jump over canyons. The Swamp Boat and Drop Ship from the original Killzone are used by NPC’s but are not usable by the player.
The main character in the campaign and a captain in the ISA Special Forces
Luger is an Assassin for the ISA. She is a Shadow Marshal for the ISA Special Forces. She accompanies Templar during one mission.
Rico is Templars main ally in the battlefield. He accompanies him on many missions, and saves him from an ambush at one point.
A general for the ISA. At the start of the game he is at the Rayhoven Base when it is attacked by the Helghast.
Weapons researcher who designed a nuclear bomb for use on the Halghast’s home planet. She is at Rayhoven Base during the invasion, with General Stratson and Heff Milcher
Heff Milcher has been the Defense Minister for the ISA Government for two months and plans to retire after the conflict. He is at Rayhoven Base for the crysis meeting with General Stratson and Evelyn Batton.
The Helghast General tasked with invading southern Vekta.
Colonel serving under General Metrac. Recruited for the war by Metrac himself, he is always doing important missions for Metrac. He is tasked with capturing General Stratson, Evelyn Batton and Heff Milcher in order to find the nuclear missiles.