Rambo is an overhead action shoot-'em-up in the vein of Commando and Ikari Warriors. The first player controls Rambo, who is armed with an M-60 machine gun with unlimited ammunition (which can only fire two shots on-screen) and a limited supply of explosive arrows used to take out tougher obstacles such as tanks and gates. A second player can play at the same time and control Rambo's partner Zane (a character created for the game), who wears a yellow headband. The objective of the game is to fight through the enemy's defenses, reach the gate at the end of each stage and then defeat as many enemy reinforcements as possible until the gate starts flashing in different colors. The player starts off the game with three lives and gains a new one every time he completes stage. A second player can join-in anytime during the first stage as well until the second stage, in which the game will end for either player if one loses all of his lives.
Unlike the aforementioned games, the player can only shoot his weapons in five directions (left, up, right, or diagonally up-left or up-right), even though movement is allowed for all eight basic directions. When the player moves downward, he will his weapon aimed upwards. However, enemies can shoot upwards in diagonal. Power-ups are obtained by killing a specific amount of enemy soldiers or as bonuses from the prisoners when they are freed from the huts located throughout the first four stages (which are only destroyable with arrows). Only one power-up can be on screen at a time, so if there's one dropped by an enemy at the time a prisoner should drop another, the prisoner will simply leave. These power-ups allow the player to increase the range of his shots, speed, increase the number of arrows and improving the firepower of the arrows hitting in four directions after the first explosion. There are also "?" marked which can kill all enemies in the screen or add a life.
The player starts out each life with a supply of five explosive arrows and every time he picks an item (no matter which one is it), he gains two more (although the in-game counter maxes out at "9", the player can actually carry more than that).
Rambo was originally released in Japan as Ashura. The Japanese version of the game had players controlling a pair of armed Buddhist monks named Ashura and Bishamon, who are on a mission to rescue their kidnapped friends from the enemy.
When the game was being localized for the American market, Sega bought the license to base the game on Rambo: First Blood Part II. The Player 1 character was redesigned to resemble Rambo, while Player 2 was replaced with a similar character who serves as Rambo's partner. The artwork on the title screen was replaced with a reproduction of Sylvester Stallone's pose from the film's theatrical poster, while the original title theme was replaced by a PSG rendition of Jerry Goldsmith's theme music from the movie. Some adjustments were also made to the game's difficulty (flamethrower soldiers for example, who could only could be killed using arrows in Ashura, are now vulnerable to regular gunshots in Rambo). The visuals on the Stage Clear screen, which originally showed various Asian landscapes and buildings in Ashura, were replaced with images of Rambo in various action poses.
The game was modified again for its release in PAL territories, as the Rambo license was only usable for its North American release. As a result, the PAL version, Secret Command, combines elements from the previous two versions. The main characters are referred to as "Bishamon" and "Ashura" in the manual, but they still retain their designs from Rambo. The title music is also the same one from Ashura, but the artwork is different. The Stage Clear visuals are once again illustrations of Asian landscapes.
Both the Japanese (Ashura) and European (Secret Command) versions would later be released for the Wii Virtual Console, in their original release regions. Secret Command was also be released for the North American VC service as well, as an "Import" title.