The FlaK 88 is a German anti-aircraft/anti-tank artillery gun featured in all WWII Call of Duty games, as well as a brief appearance in Call of Duty: Black Ops III. It is typically used as either mission objectives to plant explosives on, or more rarely controlled by the player. FlaK is a contraction of Flugzeugabwehr-Kanone meaning "anti-aircraft gun" (hence the final K being capitalised), and the name is a nickname; commonly just called the 88 regardless of version.
In other missions, the player is assigned to destroy FlaKs; this is done in "Brecourt", at the base of "The Eder Dam" and in "Berlin". Typically this is performed by planting timed explosives on them. They also appear as objectives during the second tank level in the Russian campaign, "Oder River Town"; here, they can be destroyed by simply firing at them with the T-34's main gun.
FlaK guns are usable in Call of Duty: United Offensive multiplayer. They are very powerful anti-tank weapons, capable of destroying tanks with at most two shots and tank destroyers with at most three. They are invulnerable, making them very useful. However, the player can still be killed while using one, so it should be used with caution.
The player fires the gun from the fuze setter's position on the left of the cradle; the elevation and traverse handwheels are on the right, but this is the correct side to find the weapon's firing lever.
The weapon is shown as usable by a single man for gameplay purposes; the normal crew of a FlaK is ten.
Brecourt Manor's final FlaK.
The Pegasus Bridge FlaK, the first such weapon usable in the series.
The last FlaK in the Berlin level, the final objective before commencing the assault on the Reichstag.
A FlaK 88 in the Eder Dam.
Call of Duty 2
In Call of Duty 2, the FlaK 88 has regressed back to its role as a mission target. They can be used at many different times, but they're only required in "Hold The Line". Call of Duty 2 uses the same white crosshair for them as is used for other fixed weapons.
The CoD2 FlaK slightly alters the player's point of view compared to the original, but still positions them at the firing lever.
A FlaK battery in desert camouflage overlooking a harbour.
Call of Duty 2: Big Red One
"This 88mm caliber German anti-aircraft gun was often also used for anti-armor purposes. 20 rounds-per-minute rate of fire."
— Bonus Materials description
In Call of Duty 2: Big Red One, the player takes control of a Flak 88 (referred to as Flak 88 gun in the HUD) in order to destroy enemy bunkers in "The Great Crusade". It is the only time a Flak 88 is used in Call of Duty: Big Red One. The player can use an over the top first-person view on the gun and can still take damage while using the Flak 88.
Call of Duty 3
"8.8cm FlaK 36/37 "FlaK 88". Dreaded German anti-aircraft cannon developed in the 1930s and used infamously in anti-tank and artillery roles. 88mm high explosive, anti-tank rounds able to defeat 150mm armor at 2 kilometers."
— In-game description
In Call of Duty 3, the player is tasked with destroying FlaK 88's in the levels "Night Drop" and "Laison River". They may have to destroy them by taking out their crews or by placing explosive charges on them.
In Call of Duty: World at WarFlaK 88s are featured in the levels "Vendetta," "Blood and Iron" and "Heart of the Reich." They are featured as enemies during the tank-driving mission "Blood and Iron" and explosives must be planted on several guns during "Heart of the Reich." The FlaK 88s are unusable by the player. At this point, the player gets checkpoints by destroying the first two, then the last two.