My favorite aspect of this shooter is its atypical music, not only for the excellence of the compositions themselves but also for the distinct audio quality. It's not the same sort of stuff you can hear from the lauded Dungeon Explorer and The Legendary Axe II soundtracks--in fact, it's very bizarre and very different from any other HuCard-presented material I can think of--but it's immensely impressive, frequently frantic, and extremely compelling. Consider this title a good reference point for misguided fools who believe the TG-16's aural capabilities don't extend beyond NES-caliber sound.
Aside from its intense, atmospheric score, Psychosis is best known for its intriguing "delve inside a troubled mind" theme (your mission is to enter a girl's subconscious and preserve her sanity by obliterating the nightmarish images that have tormented her), and it really takes advantage of the concept with an awesome ship design, outlandish enemies, and a generally abstract feeling about the realm it takes place in.
I first played Psychosis back when it was originally released, and every time I revisit it, I find myself pleased to discover that it holds up extremely well. In fact, I enjoy it now more than ever. Unfortunately, it's cake for good shooter players. I can blast through it without dying and with no practice, and at five stages, it's far too short. Considering how enjoyable the game is, though, its relative lack of difficulty needn't be viewed as a deterrent. And it does loop with a "World II" that features identical level layouts but bullets that fly at insane speeds and foes who can really take a pounding.
The fox boss shouldn't present much of a challenge, but the guy with the large knives will be a totally different story until you figure out his pattern.