Use the left and right arrow keys to move and the up key to jump. You can double-jump. The down arrow makes you crouch. While crouching you fall faster in the air, but cannot move side to side. If you crouch and then jump right after, you will perform a super jump. The goal of the game is to survive as long as possible, as you get points for each bullet you dodge. If you touch the bottom or left side of the map, the game ends. You can jump on top of bullets, but if you get hit by them, you'll probably get pinned to the wall. The difficulty steadily increases as time passes, but if you want to skip to the hardest difficulty, select Intense mode.
I made everything myself except for the background, which is from the website below. (Sorry about the bad art) http://thekaratekidblog.blogspot.com/2018/11/ninja-dojo.html