Call of Duty: Unseen Battles

"Call of Duty: Unseen Battles" is a first-person shooter in the series, developed by Treyarch and published by Activision. It takes place in the battles that are unseen, untold and unheard from the various wars.

Gameplay
The players can make their own decisions that affect the storyline, like they did in Black Ops II. The gore and blood system are now upgraded to a better version. Examples include: Ripping skull in half if they get shot by any rifles, exposed intensines after being perporated by machine gun fire or being blown up by artillery and bombs/grenades and torn-apart hands. Additionally, the players can now slide, mantle, climb up, crawl, swim, lean side and run while firing. Moreover, the weapons and vehicles are specifically chosen for the historic period. Like Black Ops series, the player characters can talk in cutscenes and gameplay.

Story/Campaign
In Campaign mode, you can play as both sides: Entente and the Central Powers on the first chapter, Allied and Axis on the second chapter and last but not least: French Foreign Legion, Turkish Brigade, People's Liberation of Army, North Vietnamese Army, Vietcong, USMC 26th Marine Regiment, Soviet Army and Mujahidden in the third and last chapter.

The Great War (ACT 1)
In "The Great War" chapter of the campaign mode, you start as Pvt. Nebojsa Djordic of the Serbian 1st Combined Division in the Battle of Cer. He, along with 250 soldiers, attacks an Austro-Hungarian outpost on the slopes of Cer Mountain. His commander, Cpt. Luka Ivanic, orders Nebojsa to level the outpost or clear the same place with his men: Then, the perspective switches to the tall German soldier, Cpl. Kuno Adalwulf, who fights in the Battle of Tannenberg. He is ordered to repel the Russians by Sgt. König Strauss and succeeds in doing so. When he was about to win the battle, a last standing Russian soldier draws his Shashka so he must be careful in this QTE (This is a key for Kuno's survival): In both endings of QTE, the Germans win the battle.
 * If the player chooses to level the outpost, he sends his closest friend Miroslav Luksic to the HQ and Miroslav tells the artillery unit to level the place. The artillery unit gets perplexed but nevertheless obliges his orders. The artillery then fires upon the outpost, obliterating the place and resulting in death of Nebojsa, Cpt. Luka and 198 Serbian soldiers. Later, we see the Serbians retake Sabac. This marks the end for the battle of Cer.
 * If he chooses to clear the area, the mission will take longer but he and his brothers in arms succeed in repelling the Austro-Hungarian troops. Several days later, we see Nebojsa raising the Serbian flag over Sabac and his Cpt. Luka having drink with Miroslav. The Serbians still win the battle.
 * If he dodges the sword Russian soldier was carrying, he grabs his left arm and stabs him in the face with Sturmmesser, killing him instantly.
 * If he fails to dodge or doesn't do anything at all, Russian does four scars on Kuno's torso and makes him die. Sgt. König then takes his revenge by shooting the Russian in the head with Mauser C96.

On the morning of 10th August, at 4:30 a.m., an Ottoman soldier named "İbrahimoğlu Hüseyin" is seen lunging forward with his brothers in arms towards the ANZAC trenches down the hill in Chunuk Bair. Hours after, the Ottomans retake the hill.

In Battle of Verdun, you play as Sgt. Jean Leon-Régis of the French Army. He delivers a speech about how Joan d'Arc and Napoleon conquered their heart and adds "Now it's our turn to conquer those two's heart". He then says the famous motto: "On ne passeront pas!" ("They Shall Not Pass!" in French). Then, he leads the charge. During the charge, he gets stuck in the mud and tries to stand up but he fails. A QTE then occurs: After the Battle of Verdun, we start to play as Laurent Campbell, a young Canadian soldier in Battle of Passchendaele. Under heavy rain, he gives the Germans everything he got. Then, one of the German soldiers has a brutal combat with Laurent but Laurent draws his precious knife and stabs him in the heart, killing him. His commander, Cpt. Serge, marches towards the German trenches but they get mowed down by machine-gun fire. Then, they all die in the mud.
 * If Kuno survives in the Battle of Tannenberg, he cleans the mud with Feldspaten M1887 and helps him stand up. Jean asks why Kuno helped him, he simply replies: Always stay hopeful and guardian angel will save you. In the end of Battle for Verdun, he looks at the sky and says: "Mon dieu. I thank you so much."
 * If Kuno dies in Tannenberg, he sees many of his men getting slaughtered and dies by drowning to the death. The battle still ends in being victorious for the French Army.

The perspective switches to the Austro-Hungarian side with a soldier named "Adelbert Farkas" from Battle of Caporetto. With Germans' lethal gas attack, the Italians panic and have confusion. Adelbert, equipped with a light-machine gun, fight the panicking Italians from the behind and outflank their position. After that, he celebrates the victory by shooting his machine-gun in the sky.

In Meuse-Argonne Offensive, the perspective is switched to a US Doughboy named "James Kimberley". He, along with his lost battalion, must hold the Germans off. He takes a severely wounded pigeon and writes the message to stop the artillery barrage. He succeeds in doing so and the battalion is saved.

Finally, we see the ANZAC's side from Lewis Rain's perspective. He's the commander of a light cavalry regiment. He encircles the survived 8th and 4th Army's soldiers and defeats them all. After this battle, he sighs in relief and says "The Armageddon is over". This marks the end of the Act I.

The Great War (ACT 1)

 * The Day That Shook The World (Battle of Cer)
 * Tannenberg (Battle of Tannenberg)
 * Turning the Tide (Gallipoli Campaign)
 * Guardian Angel (Battle of Verdun)
 * The Price of a Mile (Battle of Passchendaele)
 * Caporetto! (12th Battle of Isonzo)
 * The Lost Battalion (Meuse-Argonne Offensive)
 * The Final Battle (Battle of Megiddo)

The 6-Year War

 * Blitzkrieg (Invasion of Poland)
 * White Death (Simo Hayha, The Winter War)
 * No Surrender! (Siege of Tobruk)
 * Union (Battle of Monte Cassino)
 * Rage in the Skies (Battle of Midway)
 * Hearts of Iron (Rescue Operation at the Elbe River)
 * August Storm (Manchurian Strategic Offensive)

The Hot Battles On The Cold Earth (ACT 3)

 * La Legionnaire (Battle of Mang Yang Pass)
 * First Attack (Battle of Kumyangjang-ni)
 * Great Salvation (Battle of Kunu-ri)
 * Unavoiadble Blow (Fall of Lang Vei)
 * Khe Sanh (Siege of Khe Sanh)
 * Thousand-Yard Stare (Fall of Saigon)
 * Desert Warriors (Soviet-Afghan War)

Melee Weapons

 * US Trench Knife M1918
 * Enveriye Dagger
 * Sturmmesser
 * Hungarian sturmtruppen knife
 * Italian Arditi dagger
 * Turkish Trench Club
 * Trench Club
 * M1881 Shashka
 * M1861 Offiziersabel
 * Feldspaten M1887
 * Couteau Mle 1916 "Le Vengeur"
 * Boker M1915
 * Modello 39 Combat Knife
 * Fairbarn Sykes Knife
 * Heer knife
 * Puukko
 * M1940 knife

Pistols and Revolvers

 * Mauser C96
 * S&W .45 ACP M1917
 * M1911 .45
 * Modelle 1892
 * Glisenti M910
 * Luger P08
 * Nagant M1895
 * Steyr M1912
 * Chamelot Delvigne
 * Bode M1889
 * Montenegrin Gasser
 * Webley Mk. I
 * Walther P38
 * Tokarev TT-33
 * Beretta M1934
 * Webley Mk. VI
 * Enfield No. 2 Mk I
 * Makarov PM

Sub-Machine Guns

 * MP38 / MP40
 * PPSh-41
 * PPS-42
 * Thompson M1A1 / M1928 / M1928A1
 * Grease Gun
 * MAT 49
 * K-50M
 * MAB 38
 * MAT 49
 * FNAB-43
 * OVP M1918
 * Sten Mk. II / Sten Mk. V
 * Suomi KP-31
 * KP-44

Bolt-Action / Lever Action Rifles

 * RSC 1917
 * Lebel M1886
 * Gewehr M1898
 * Lee Enfield Mk. III No.(I)
 * M1910 Ross Mk. III
 * M1917 Enfield
 * Lee Enfield Mk:I No.(4)
 * Turkish Mauser M1903
 * Carcano M91
 * Mosin Nagant M-91
 * Steyr Mannlicher M1895
 * Serbian M1889 / M1890
 * M1 Carbine
 * M1A1 Carbine
 * Mosin Nagant M91/30
 * SVT-40
 * Wz.29 Mauser
 * MAS-36
 * Karabiner 98k
 * Gewehr 43
 * Arisaka Type 99
 * Winchester M1895 Russian

Assault Rifles / Carbines

 * Mkb. 42 (H)
 * STG-44
 * AKM
 * Norinco Type 56
 * Colt M16A1
 * XM177E1
 * AK-74
 * AKS-74

Light-Machine Guns

 * BAR M1918
 * Lewis M1914
 * Madsen M1902
 * Bergmann MG15 n.A
 * Maxim MG08/15
 * FM M1915 C.S.R.G. "Chauchat"
 * Browning M1918A2
 * DP-28
 * LS-26
 * Browning Wz.28
 * MG-34
 * MG-42
 * Type 99 LMG
 * RPK-74
 * RPK
 * M60
 * MAC FM24/29
 * PKM