Use arrow keys to try to dodge the arrows. Timer accurate to 0.1 seconds. Press the space bar to restart if you are too lazy to press the green flag like me. Restart button also works. Press the "e" key for easy mode (automatic if you press the restart button, the green flag, or the space bar), press the "M" key for medium, and press the "H" key for hard. The higher the difficulty, the faster arrows spawn, the larger they get, and the faster they become. Good luck!
Thanks to Wuxabaca and Gure_Kwin!