Front Mission: Gun Hazard

"Front Mission: Gun Hazard (フロントミッションシリーズ ガンハザード Furonto Misshon Shirīzu Gan Hazādo) is a scrolling shooter video game developed by Omiya Soft (the same team that developed the original Cybernator) and published by Squaresoft. It was released exclusively in Japan on February 23, 1996 for the Nintendo Super Famicom game system. A translation patch was for the game was released in August 13, 2004 by the group Aeon Genesis, translating the entire game to English. The game is spin-off in the near-future, mecha-themed Front Mission series. It became available on Japanese Wii's Virtual Console service on May 20, 2008.

Unlike other Front Mission titles, Gunhazard is a side scrolling shooter game akin to Cybernator. There is a large amount of customization of your mecha and you can also choose a partner to help support you in battles. The main character can also exit their mecha to reach certain areas. After completing the first set of levels, three areas open up. It is up to the player which order they complete the levels."

Source: Wikipedia, "Front Mission: Gun Hazard," available under the CC-BY-SA License.