The MSX Gradius 2 is unrelated to Gofer no Yabō (which used the Roman numeral 'II'). Instead of controlling Vic Viper, the available ship is called "Metalion" (code name N322). This game also has some semblance of a storyline, which is told by cut-scenes. The gameplay is mostly unchanged from the rest of the series, though there are some power-ups that temporarily gives the ship some enhancements. In addition, when the bosses are being defeated, if the Metalion flies where they are, a mini-level can be accessed in order to obtain new permanent upgrades, assured that the mini levels are successfully cleared. This version was ported to the Sharp X68000 computer under the name Nemesis '90 Kai, with a number of graphical and aural enhancements.
The first Gradius for a portable system, in this case Nintendo's Game Boy. The name Nemesis was kept for the game's worldwide release. It combined elements from Gradius and Gradius 2 (the MSX versions), as well as some all-new features.
Another Gradius game exclusively for the Game Boy. It was one of the larger Game Boy carts in existence at the time (2-Megabits), and was completely different from the rest of the series - most of them used music, enemies, bosses and even levels from previous games in the series, but this one did not, except for the boss music from the first Gradius game with the addition of a small original part to the piece. A little bit of the "between levels" music from Gradius III can also be found at the very first part of the game. It was released as Nemesis II in Japan and as Nemesis II: Return of the Hero in Europe.
Other horizontally-scrolling shooter game developed and published by Konami in March 1, 2004 for mobile phones, and was released on NTT DoCoMo's FOMA 900i line of phones in Japan.In contrast to other Gradius games, players control the opposing force in form of a Big Core. However, since the Big Core you take control in this game is a betrayer ship escaping from Lars Empire, which was the enemy in Gradius NEO, you won't fight against the Gradius Union.