I played the Windows version in Wine on Linux.
I did not read "how to play", and I immediately regretted it. I restarted the game and read.
I found I could not defeat the enemy ninjas, so I ran past them.
Eventually, I fell through the world, and this condition was not detected.
Overall: Fighting games are very difficult to make, and this shows off why that is. The punches and kicks are unsatisfying and are difficult to land. The enemy ninjas feel much more powerful and numerous than you. It looks like a bit of a grind to go through the game, based on the number of enemy ninjas I saw in the first few areas.
Fun: defeated zero ninjas
90s: This might be able to run on certain powerful 90s arcade machines or a Dreamcast
Visuals: It is very clear that a lot of work went in to creating the environments. It's a shame that being able to enjoy the environments is obstructed by the poorly tuned fixed camera system.
I think you should continue to try to make a better fixed camera system. This is more work than manual control, because it of course requires extensive testing, and probably no shortage of deep understanding of quaternion rotation magics in order to execute the way you appear to have wanted this to work.
Sound: I liked the soundtrack--fit the game well.