Nemesis is the first portable game in the Gradius series, released for the Game Boy in 1990. The game has five stages and plays similarly to previous Gradius games. It was released in North America and Japan.
This game allows the player to select the stage and the number of available extra lives from the very start.
This is also the only game in the series to use the European name of the Gradius series, "Nemesis", internationally.
The game was later included in the compilation Konami GB Collection Vol. 1, where it is titled Gradius.
Nemesis retains the basic power-up meter commonly used in most Gradius games, but with the addition of multi-level missiles not present in the original Gradius
The game consists of only five stages, each with a unique core boss. Although it is also possible to access hidden bonus stages in which the player may collect 1-ups and score bonus cells. Likewise to other Game Boy titles developed by Konami, the game presents the player with a stage selection screen before starting.