Sitting in a top secret bunker one night puzzling over some challenging physics problems, some futuristic artifacts are amazingly teleported to the player—in the role of a US Army scientist—along with a note that says the artifacts are from the future, a future in which the Nazis won World War II and subsequently were able to enslave the entire world. The scientists who sent the artifacts did so in a hope that the player could reverse the outcome of the war, a war Nazi Germany should have rightfully lost.

The success of the Nazis is based on their use of a mineral named lunarium, which has the ability to lower the IQ of human males drastically, thus effectively preventing military resistance when the Nazis invade. The lunarium is dropped in the form of bombs from a fleet of zeppelins flying at a higher altitude than anti-aircraft guns could possibly reach. What is even more puzzling is that lunarium is - as the name indicates - only mineable on the Moon, and mankind so far does not yet have the technology to reach it.

Using a rocket pack and a radium pistol, the player must fly around the world fighting the escalating Nazi technology. Sometimes this includes shooting down enemy fighters with the radium pistol to intercept enemy shipments. Sometimes the sequences degenerate into bareknuckle fistfights with enemy Nazi guards in order to gain rocket parts, and sometimes he has to disable the defenses of two available lunarium depots to get fuel for both his own rocket pack and the rocket ship he must assemble.

From time to time, the hero must catch up with a kidnapped scientist and his voluptuous daughter (the love interest for the game) in a zeppelin. In these encounters the player must engage in dialogue with them (notably for the time, featuring digitized speech) to win their trust.

One part of the game takes the form of a strategy game: from a world map display the player directs five agents to search for hidden Nazi bases and they can also "organise resistance" to slow the enemy's advance towards the USA.

The ultimate goal of the game is to collect five parts for a rocket ship and 500 units of lunarium to get to the Moon and close down the mines. But as it turns out, the Nazis were not the only ones involved in the scheme: an "Interplanetary Union of Fascists", which was formed by aliens, have struck a deal with the Germans. In order to achieve final victory, the Rocket Ranger must battle one of these aliens.

To fly from location to location, the rocket pack must be filled with a very specific amount of fuel. Too much or too little will cause the hero to overshoot or fall short of the target, and as a result plunge to his death. The player could determine the correct amount of fuel for a starting/destination pair using an encoding wheel included with the game. This element of the game was actually a form of copy protection. The idea was that since the wheel was included with the game and couldn't easily be duplicated, only legitimate purchasers of the game could successfully use the game.

Because the wheel needed to be used for every trip the Ranger made, it got heavy use. As a result, the wheel often fell apart (the front part of the wheel became separated from the back) after several games. The wheels could still be used, but is was more difficult when they weren't connected. Therefore, some users constructed tables that included all of the codes needed to travel from one location to another. These tables eventually made their way to bulletin board systems and (later) the Internet and used as a tool for pirated versions of the game.

Like most Cinemaware titles, this game was originally developed on the Amiga, one of the more capable home computers of the era. It was later ported to the other platforms, scaling down the graphic and sound quality to the best those systems could deliver. The other platforms this title was ported to includes Atari ST, MS-DOS, Commodore 64 and Nintendo Entertainment System. In 1989 an Apple IIGS port was released, with a vastly superior musical soundtrack score (in terms of music synthesis quality) composed by Bob Lindstrom, with graphics comparable to the original.

• A different Amiga version of the game exists with invading extraterrestrial aliens being the culprit, instead of German Nazis. This is a localised version for Germany, where references to Nazis and swastikas were not allowed in video games at the time, not even as antagonists. However, the original designs were retained, which raised logical questions about why aliens would adopt German WW2 technology and be largely successful with it. This version was also the basis for the NES port, due to Nintendo's strict content restrictions at the time.

• Between 1991 and 1992, Malibu Comics published a Rocket Ranger comic series closely based on the computer game. In the series, the Rocket Ranger—here named Tom Cory—comes to fight Oberst Leermeister, the German officer who oversees the lunarium operation, personally (in the game, Leermeister was more a background character, although it was possible to come face to face with him, in an interrogation sequence). Only five issues were produced, although the open ending at the end of the fifth volume suggests the planned release of at least one sixth issue containing the climactic end battles.

Computer Gaming World had high praise for the game, saying "It blends action and strategy nicely and supports an entertaining game with wonderful graphics and sound." However, the lack of a save-game feature made the game frustrating to play.

The game was voted Best 16-bit Graphics of the Year at the Golden Joystick Awards.