In Secret Weapons of WWII, players will engage in war with a choice of up to 46 vehicles to control. In addition to the 30 vehicles introduced in the original game such as fighter planes, tanks, and aircraft carriers, players can operate16 new vehicles including the Horton HO 229 "Flying Wing" that is equipped with 30 mm machine guns and missiles. Other vehicles consist of a US Sherman tank with a T-34 Calliope rocket launcher, U.S. T95/T28 Super Heavy Tank, the Sturmtiger (naval gun mounted on Tiger tank), U.S. Goblin jetfighter, C-47 cargo plane that will serve as a mobile spawn point, the American Armstrong Whitworth AW-52 advanced fighter, the German Wasserfall guided anti-air missile and the German Natter rocket plane. Also, for the first time, Secret Weapons of WWII will give players the chance to fly and fight at the same time with a top secret German prototype Rocket Pack.

There will be seven new weapons including one-shot kill knives. Other weapons include the Bren light machine gun, Remington Auto 5 shotgun and the Mauser K98 grenade rifle. Players can put these weapons to use in eight fresh World War II combat campaigns including PeenemŘende, a V2 research facility, and The Eagle's Nest, Hitler's hideaway. All new battlefields offer unique settings ranging from nightfall during the summer in Prague to a winter battle in Norway.

In addition to offering innovative weapons and vehicles, the game introduces British Commando and German Elite troops while enriching gameplay by adding a new "objective based" gameplay mode. In this new mode, players will be tasked with a specific objective such as destroying a secret facility in order to win the battle.