Exerion
Platform: MSX
Region: Japan
Media: Cartridge
Controller: Keyboard, Joystick
Genre: Shoot 'em Up > Vertical 
Gametype: Undefined
Release Year: 1984
Developer: Jaleco
Publisher: Dempa Shimbunsha
Players: 1 - 2
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This is a shoot-em-up game with parallax effects in the background. It does have a simulation of inertia in the control of the ship.
There are dozens of enemies and two types of shooting: slow and fast. Two weapon systems: one slow double-shot cannon and one fast single-shot cannon.
With each enemy hit by the slow cannon you get one shot added to the fast cannon ammunition supply.
A challenge stage follows each stage in which you can build up your fast-shot bullet supply.
 
http://www.mobygames.com/game/msx/exerion