The player sends the title character (who did not have a proper name in the Japanese version) through a number of fantastic settings with the ultimate goal of defeating the evil King Ligar in order to restore peace to the realm of Argool (Argos in the Japanese version). To accomplish this goal, Rygar/the Warrior must visit five Indora gods who present him with essential items needed for completion of the game. Each of the Indora gods is located in a different realm, and is almost always guarded by a boss. The player can choose the order in which some stages are played, but since certain items are required to reach new areas, choices are somewhat limited. After playing through the five major realms of the game, he must journey to King Ligar's flying castle for the final confrontation.
The NES version is an open-ended, action-adventure game like Metroid. It was particularly notable for its permanent power-up mechanic, which at the time blurred the line between the power-ups used in action-adventures and the experience points used in RPGs.
The NES version of Rygar did not allow for game saves. The cartridge did not contain a battery, nor did it contain a password feature. As a result, many players were forced to pause the game and leave their NES on overnight.
The PAL version of the NES game reportedly contained a computer error which inadvertently increased (substantially) the difficulty in the final portions of the game, particularly in beating the final boss.