Gradius: The Interstellar Assault is the second portable game in the Gradius series, originally released in Japan for the Game Boy in 1992. It was released in 1991 in Japan as Nemesis II: Return of the Hero. It is also a sequel to the Game Boy game, Nemesis. Both games can be considered a spin-off of the main series, but unlike Salamander and Gradius Gaiden, they don't appear to be part of the official Gradius canon seen in Gradius Galaxies.
Once again the player takes control of the Vic Viper and flies through five different stages destroying Bacterian's army. However, unlike most of the games in the series, the game lacks many reoccurring themes that have become a staple of the series. Some of the more popular elements missing from this game are: A moai stage or any moai enemies, classic Gradius stages, classic Gradius music, and the traditional giant entity that is unprotected and serves as a final boss. There are, however, a handful of classic elements that are present such as Core bosses and even a portion where the Vic Viper must maneuver around a countless array of tiny spaceships like those featured in the original Gradius.
The game retains the traditional power-up bar from the original Gradius games. As usual the player can speed-up multiple times, use missiles, shoot double firepower or lasers, use several Options at a time and use the classic shield (although it is referred to as a force-field). However, before each game is started or continued, the player is given a "Weapon Select" screen. Here the player can choose between one of three settings for the missiles, double firepower, and lasers:
- Missiles Options - Normal, 2 Way, or Tail. The 2-way missile is of the Salamander variety, not of the Gradius variety. That is to say, rather than falling out from your ship from the top and bottom, these missiles will travel along the lower and upper surface of the level as well.
- Double Firepower Options - Normal, Twin Cannon, or Tail Gun
- Laser Options - Normal, Twin, or Ripple
Note: Boss names in italic are unnoficial
|1||Remains||Infected Statue||A Chase|
|2||Battleship Interior||Core Reactor||Courage|
|3||Asteroid Belt||Crater Core||Dodge|
|4||Planet Surface||Fortress Gate||Oddplanet|
|Game Boy Gradius games|
|Ships||Vic Viper • Coreship|
|Nemesis Stages||Volcano • Cell • Moai • Bone • Fortress|
|Gradius: The Interstellar Assault Stages||Remains • Battleship Interior • Asteroid Belt • Planet Surface • Fortress|
|Nemesis Bosses||Volcano • Super Big Core • Zub Rush • Crawler • Zigzag • Striker • Amb • Reckless • Mother Computer Z|
|Gradius: The Interstellar Assault Bosses||Infected Statue • Core Reactor • Volcano Core • Fortress Gate • Guardian Core • Escape Ship|
|Gradius Video Games|
|Gradius series||Gradius • Gradius II • Gradius III • Gradius Gaiden • Gradius IV • Gradius Galaxies • Gradius V • Gradius ReBirth • Gradius: The Interstellar Assault • Gradius NEO • Gradius NEO Imperial|
|Spin-offs||Salamander (Life Force) (MSX ver.)• Salamander 2 • Nemesis 2 (Nemesis '90 Kai) • Nemesis 3 • Nemesis (Game Boy) • Cosmic Wars • Solar Assault|
|Parody games||Parodius • Parodius Da! • Gokujō Parodius! • Jikkyō Oshaberi Parodius • Sexy Parodius • Paro Wars • Otomedius (Otomedius Gorgeous) • Otomedius X: Excellent!|
|Other games||Scramble • Thunder Cross • Thunder Cross II • Space Manbow • Force Gear|
|Pachislot||Gradius: The Slot • CR Parodius Da! EX • Gokuraku Parodius|
|Cancelled||Vic Viper • Gradius Arc • Salamander HD Remaster|