A Genesis exclusive, Trouble Shooter was released in 1991 (at the dawn of the Genesis/SNES rivalry). In it's native Japan it was known as Battle Mania and was developed by Vic Tokai.
The plot of Trouble Shooter is a tongue in cheek take on the save the princess concept, with the player taking on the role of a duo of teenage girl super mercenaries in a scifi setting heading out to rescue a prince before his abduction can cause a major international incident.
Gameplaywise Trouble Shooter is a quirky side Scrolling shooter that is visually inspired by teenage school girl anime shows and combines elements from R-Type and other Action games. The most unique aspect of the game mechanic is that we control a duo of teenage super mercenaries. The second of which (the side kick, who is also imune from hits) can be switched between firing backwards and forwards. In addition to the two way shooting mechanic, there is also a special move accessory which the player can choose from a selection of available options at the beginning of each level.
The enemy waves are varied and the action clear. Some critiques of the game at the time of its release concentrated largely on the lack of a multiplayer mode and the relatively slow turn around time of your companion. The game also only gives the player one life (with a set number of hits that can be taken) and no continues. Despite this the game got positive reviews, being a well designed and entertaining shooter.
Vic Tokai was a bit of an unusual developer that felt almost like a pre-crash fly by nighter, being the subsidiary of a major telecom company. This "cash-in" feel lead to a variety of games being developed on a plethora of platforms ranging from the C64 to the N64, without any Major concentration developing on a single system. This did not mean they produced bad games though, giving us high water marks like The Mafat Conspiracy, The Gene Machine and Shinobi Legions. But there were also some serious turds in the pile as well (Aero Fighters on N64 and Top Gear 2 on CD32 come to mind).
Trouble Shooter did get a sequel, that never made it to the USA or Europe. In it there were some clear references to the developer's less than positive views of Nintendo and the SNES, making the game a bit of a cult classic for the Genesis community.