I recently discovered this and the game really fascinates me. It's one of the simplest games you could imagine yet great fun and actually pretty addicting!
I'd suggest some minor changes, though... that's just what I thought about while playing. I do think that it is pretty perfect in itself already but maybe some of those things might make the game even more fun to play: (most of those things should also be quite easy to integrate)
a.) The game really tends to get ridiculous at some point. Am I just not far enough or does the difficulty-curve's slope flatten at some specific point? I guess it should, because just surviving is already challenge enough at a certain level of difficulty. It would also make the highscore-system more... I don't know... motivating? Mostly because the highscores wouldn't seem as "hit into stone" as they are now. You really need godly reflexes to just pass a certain point.
b.) I like how reflected projectiles can kill flying ninjas... maybe the game could underline that mechanic a bit more as in (example):
- Reflected Star Kills Ninja: +1 bonus score. (so 3 in total for 1 star, 1 ninja, 1 "combo")
- Killed Ninja collides with another Ninja (which could be integrated as another killing-method?): + 1 bonus score.
- Ninja who was killed with a star collides with another Ninja: + 1 bonus score.
- Ninja is killed with his own star: +2 bonus score.
You could also play some kind of sound (like a "BONZAI"-cry or something) if a bonus-score is earned. A more high-pitched sound following up in case of a ninja->star->ninja combo might even enhance the "Peggle-Effect"
This might not have to do very much with strategy or skill but it could render the game more enjoyable as shown in the popular "casual game" Peggle (a Pachinko-clone).
c.) You could slightly alter the sword-controls to make them more ergonomic. A suggestion:
Down: Does nothing
Up : Lifts the sword straight up into the air. (not really a defensive maneuver but a nice tool to enable the player to kill some ninjas or
shourikens that fly around above his head and earn bonus-points)
Right : Does exactly the same as it uses to.
Left : Does Exactly the same as it uses to.
UpLeft: Does exactly the same as it uses to.
RightLeft: Does exactly the same as it uses to.
RightDown: Low diagonal sword position. (blocking his feet)
LeftDown: Low diagonal sword position. (blocking his feet)
And a graphical detail: Maybe the Samurai should memorize in which direction his last stance faced so if he hits to his left his "standing"-animation is also mirrored until he guards his right again. It appears slightly odd that the the character is facing right all the time.
Those were just some suggestions... not really critique or anything... hope you appreciate them.