General tricks

Skipping cutscenes with B instead of A

B skips “cutscene series” while A only skips an element of the series.

Weapon menu glitch

If you move while pressing select, you can get closer to the side of the level (required to OoB). Found by igorrson, clicky for video.

Fast turnaround

Generally you need to wait a lot of time to change your direction and go full speed. However if you hit a wall, you can instantly turnaround which usually saves time (or just simply useful for example level 1 boss fight)

Camera rules and tricks

End of screen transition

The camera has 1px/f speed, so the ninja will be transitioned with that speed. However, if your X position is higher than 225px, you will need to wait X position - 225 frames.

Scripted transitions (after flying)

You can squeze out a few X/Y position if you don't go through the transition' boundary (which would otherwise send you back pixels away).

Out of boundaries horizontally

You can go through walls if your X position is at least

Double hit with 1 shuriken

If you hit an enemy on the boundary of his hitbox, the damage will be applied twice. Doesn't works on the 1st boss.

Boss RNG

Depends on entering the level on an even or odd frame.