Hydefos

Planet Tiar is in crisis. The sunspots of this distant Earth-like planet's sun are disrupting its climate, and now evil invaders are taking advantage of this situation to try and conquer Tiar. The planet sends a distress signal to Earth, calling for a hero to fight the invader and save them. From the deep sea to the far reaches of space, it's up to you to fight and make sure Tiar does not fall.

Hydefos is a shoot 'em up with smooth scrolling, a rarity on the MSX, where the scrolling is usually choppy, and a feat developer Hertz had already accomplished on a previous title, action platformer Psychic World. You pilot one of five ships through levels featuring branching paths, so two play-throughs could be different depending on where you go.

You have a health bar, and you only die if it drops to zero or you collide with a wall. You can pick up various items that increase/decrease your speed, add guns to your ship (sometimes with the ability to rotate them to shoot up, down or behind you), give you a shield for defense, etc. The environment can also be a hazard, with walls that materialize only when shot and obstacles that need to be shot in order to pass safely.

You will regularly come across a "pit stop", where you can dock to change ships and loadout. You can also choose to bypass it and keep your current vessel. You will have to defeat four bosses before taking on the final one. Interestingly, you do not kill him, but rather catch up to him and capture him while he flees in his own ship.