Aerostar

The Good
Made in 1991 by a small studio: Sigma Pro-Tech, contracted by Vic Tokai, Aerostar is a vertical shooter, which you don't see that much on Game Boy because any type of scrolling was not really that good or sometimes even possible at the speeds a shooter requires... Even here it's a bit jerky.
It would be just another typical shooter for those days if it wasn't for one thing: the jump mechanic. You have a bar that gets filled while on ground and then you can jump or "fly" for a brief moment till your gauge is depleted, so a longer bar means the possibility of a farther jump. This affects level design - which is sort of unique on a shooter - because you move within the confines of narrow roads and platforms, the level scrolls non-stop and you get trapped, so you need to jump all the time to the next platform and carefully plan while navigating through the level, developing a certain skill to perfectly time your jumps forward, to the side and even diagonally, all these while avoiding your enemies and enemy fire.
Thankfully holding the B button lets you shoot constantly and with the A button you can even jump/evade most - not all - bullets, but alas, you cannot fire while jumping; you also have a variety of weapons to choose from that come under different power up letters - standard in shooters.
There's a certain clever unique mechanic for each single weapon but personally I'm a Contra fella, so I prefer the Spread Gun: letter "V".

The Bad
The graphics are suitable, simple if not a little bit generic, same with the music, though quite somber at times. The simplicity of these two aspects probably made the game fly under the radar.

The Bottom Line
In any case it's an amazing, unique experience for the Game Boy and for a vertical shooter that personally I didn't have anywhere else. It lights the best aspects of the Game Boy and made gold out of its limitations.