From the Avalanche Press website:
Science fiction became reality during the Second World War, as scientists and engineers labored madly to bring bizarre new weapons to the battlefield. Panzer Grenadier: Secret Weapons is a 64-page book supplement to the popular Panzer Grenadier series, looking at some of these laboratory products — all of which existed at least on the drawing board, and many of which actually saw service.
Origins Award winning author John R. Phythyon Jr. tells of odd programs like Germany's super-heavy tanks — vehicles like the 180-ton Maus tank and the equally huge Tiger III. None of those actually saw combat, but the world's first anti-tank guided missile, the German X7, apparently did.
Britain's huge tanks are also covered, with the slow and heavy Tortoise and the slow and heavy Black Prince. And there's the awesome Centurion, a design so solid it remains in service in some of the world's armies more than six decades later.
Plus we have flying machines. There are German Fl.282 helicopters (in three versions), Fa.223 helicopters (also in three versions) and the huge Fa.284 helicopter. Plus the P.1003 tilt-rotor aircraft, ancestor of the modern-day Osprey. Finally, German jets make an appearance to lend close support, including the Me.1099 attack plane fitted with a 55mm automatic cannon.
And there's more. The Americans get their Sikorsky R4 reconnaissance helicopter, while the Japanese receive the Ka-1 autogyro. For every Panzer Grenadier fan who's asked for weird science, this is exactly what you've wanted.