AI Arena

The Artificial Intelligence Arena is a large rectangular arena found in the Developer Pack DLC level of the same name. In this area, the player can set up simple matches between AI opponents, with themselves or others, in a battle to the death.

Overview
The AI Arena is comprised primarily of two main components, the platform and viewing balcony, and the arena. On the platform is the front console, a weapon selection tray, two ammo boxes, a save switch, and a day-night cycle switch (note that turning from day to night happens slowly but visibly). Walking out from the platform to the viewing balcony reveals a small scoreboard for AI Matches (similar ones can be found on both ends of the arena) and a button for more in-depth camera control. AI Matches can be set up from the front console. From here the player can select up to four slots for four different types of combatants for each of the two teams (red - left, and blue - right), and then engage them in combat. Choices for combatants available to be picked are rather limited, simply including Watchmen, Male Shrimp, Human AI with random weapons, and Nosalises. At any time the player can opt to join in on combat by jumping down into the arena - when combatants have first been selected and you join in, you will always be fighting for the red team, against the blue team. However, if you leave the arena and re-enter, you will switch sides. Remember this if you are trying to help a certain team.

Combat Analysis
The following tables has been created after viewing several matches without interference. From it it can be judged that Watchmen are the weakest AI opponents, Nosalises second, Shrimp males as second strongest, and Humans as the definite strongest, especially in groups. Note that Gank/Ganking is internet slang, short for 'Gang Killing' where a large group of players continuously spawn kill weaker enemies - in this context, the 'Gankers' are a team of four, fighting a single enemy unit.

Note: as will most kill/death ratios, the final value raises or lowers exponentially when one value nears zero. As a result, these statistics should be taken "with a grain of salt". Just because a human has a combat rating of 15, and a Watchman has a combat rating of .4 does not mean that a single human can kill 38 Watchmen. On the contrary, it means that the human unit has roughly 38 times the potential for a kill (especially in a team of other humans) than the Watchman unit does.

Challenges
On the left-hand side of the arena, underneath the scoreboard is a challenges board very much alike the one in the shooting gallery. When a challenge is accepted by pressing it's corresponding button, the player will have to perform a steadily increasing number of kills on increasingly difficult AI opponents without AI assistance or ammunition replenishes. This is, to say the least, easier said than done, as immediately the player is outnumbered. Furthermore as the waves grow in number, so to do the quantity and quality of opponents - both mutant and human.
 * Round 1, 20 Kills: Red Line Soldiers, unarmored and lightly armored, automatics.
 * Round 2, 25 Kills: Red Line Soldiers, unarmored, lightly armored, few modestly armored, automatics, some with snipers.
 * Round 3, 30 Kills: Red Line Soldiers, unarmored, most lightly armored, some modestly armored, incendiary grenades, automatics, shotguns, snipers.
 * Round 4, 35 Kills: Red Line Soldiers, unarmored, lightly armored, most lightly armored, some modestly armored, incendiary grenades, automatics, shotguns, snipers. Two watchmen.
 * Round 5, 40 Kills: Red Line Soldiers lightly armored, modestly armored, few heavily armored, incendiary and standard grenades, automatics, shotguns, snipers. Two watchmen.
 * Round 6, 45 Kills: Fourth Reich Soldiers unarmored, lightly armored, modestly armored, few heavily armored ,incendiary and standard grenades, automatics, shotguns, snipers. One nosalis.
 * Round 7, 50 Kills: Fourth Reich Soldiers unarmored, lightly armored, modestly armored, some heavily armored, incendiary and standard grenades, automatics, shotguns, snipers. Two nosalises.
 * Round 8, 55 Kills: Fourth Reich Soldiers unarmored, lightly armored, modestly armored, common heavily armored, incendiary and standard grenades, automatics, shotguns, snipers. Male shrimp.
 * Round 9, 60 Kills: Nazi Zombies with high durability, lightly armored, modestly armored, common heavily armored, incendiary and standard grenades, automatics, shotguns, snipers. A male shrimp, and a nosalis.
 * Round 10, 65 Kills: Nazi Zombies with high durability, lightly armored, modestly armored, frequent heavily armored, incendiary and standard grenades, automatics, shotguns, snipers. A male shrimp, two watchmen, and both nosalises.

Challenge Tips

 * Although it's a fairly cowardly and unexciting way of fighting, in the later rounds, hiding at the back, in the bunker areas is a good tactic to avoid being shot to pieces. Simply wait for the mutants to spawn and shotgun them, then come out of cover and pick off some infantry, then hide again when the mutants come again.
 * Don't be afraid to use grenades and incendiary grenades - incendiary grenades are the best weapon to defeat the armored Male Shrimp. These grenades prove also exceptionally useful when combined with weapons with a very long reload time, such as the Abzats or the Gatling.
 * You will only have 5 Medkits per challenge, so use them well. It's better to hide and let your health replenish if you can, but do use one if that is not an option.
 * The usage of Claymore mines is highly recommended in the later challenges. If you're struggling with the limit, these mines give you guaranteed kills.
 * The ammunition boxes disappear during a challenge, so do not waste it spraying at the enemies. Make sure you have refilled your ammo before each challenge.
 * A good tactic is to have a shotgun for Mutants and any enemies that get too close, an assault rifle for medium shooting, and a sniper to pick off targets at long range.
 * The Saiga-12 is the best shotgun to choose, especially with a drum magazine - although it has less damage per shot than other shotguns, the high rate of fire and magazine size will prove invaluable against mutants.
 * The Abzats comes a close second, with its only drawback being you cannot aim down the sights.
 * For assault rifles, the RPK-74 is a good choice, with a drum mag, as it will have good damage, high rate of fire and a huge magazine size - on later rounds, it will do a lot less damage to armored enemies, so aim for the head. However, in an emergency, you can spray at enemies and do a lot of damage before reloading, whereas rifles with smaller magazines will suffer here.
 * The Kalash is another good choice, with all the advantages of the RPK, though it has a smaller magazine size. Do not waste ammunition.
 * All of the snipers are a must, at least on the earlier rounds, with the Valve, Preved, and Hellbreath all performing well.
 * The Valve is good on mid rounds, with sufficient damage to aim for the body. On later rounds, you will need to aim for the head to do enough damage, and even that may take two or more shots. It has a fairly large magazine size (with an extended mag) so it performs well in an emergency. A laser sight and 4x Optical Scope is a must, for long and short range accuracy.
 * The Preved is more powerful than the Valve, so will be more useful in later rounds. However, it has a lower magazine size, with only 5 rounds with an extended mag. As with the Valve, a laser sight and 4x Optical scope is necessary for it to be useful.
 * The Hellbreath is probably the best sniper you could use, with high damage (provided it is charged), a large magazine size, and the ability for fully automatic fire if you are caught unaware. Unlike in the Shooting Gallery, there is no time limit, so recharge as often as you can to do the most damage, especially on later rounds. Attach the Heavy Duty Capacitor over the Extended Battery, as you will need the high power shots to do maximum damage on later rounds - frequent charging renders the battery obsolete.
 * Silencers are completely useless here, as there are no enemies to alert and all silencers do is to reduce damage, making it harder for yourself. Never use them in the challenges - the same goes for the Shooting Gallery.
 * Another possibility to successfully manage the whole challenge is the careful use of the Gatling. With an economical approach, nearly every challenge (up till stage 8) can be completed without the usage of the given ammo.
 * Later rounds can be beaten more easily if the player goes for the mutants apposed to the undead as they have less health. A Saiga-12 with a drum barrel can easily kill enough Watchmen and Nosalises before running out of ammo, with the use of a few headshots and incendary grenades for the shrimp males.
 * Helsing bolts and throwing Knifes don't disappear when the challenge starts, allowing for a large amount of ammunition to be stockpiled

Trivia

 * Note that you cannot have any allies during the challenges - it is you against everyone else.
 * While you can pre-place Claymore Mines before a challenge, there is a cap of 5. Any more will replace earlier mines.
 * The balcony area is for viewing only - although you can shoot at the enemies and they will bleed, no damage will be done.
 * The exception to this is thrown weapons. Normal grenades will will do damage to the team you last fought for, while Incendiary Grenades and Throwing Knives will do damage to either team.
 * Although enemies cannot be harmed, human enemies can have armor shot off of them, meaning they will have less protection and be more easily killed by the other team.
 * It appears that these matches don't last forever; when either side has reached 100 kills (sometimes less), both teams will disappear.
 * All the undead targets are dressed as Fourth Reich soldiers - shooting off their helmets reveals skulls with red eyes, hence 'undead'.

Bugs

 * Human AI units placed from the AI Matches never wield the Gatling correctly. Instead of holding it as a heavy weapon as they should, they tend to use it as they would an assault rifle.
 * When viewing the battle through the various cameras, there is an option to include pieces of high tempo music - however, there is no icon for what button to press to do this (PS3 confirmed), but it should be the jump button (X, A, Space Bar).
 * It's possible to refill your ammo and medkits during a challenge, to do so go in the bunker under the balcony area right next to the stairs on the side were you can select your weapons. You can reach the ammobox through the ceiling when you look into the upper corner that is adjunctive to the main arena.