The rule is simple: hit the notes when Nikochan (smiley faces) overlaps the line.
Regardless of Nikochan's position or falling direction, you can hit the notes by pressing any key on PC (except Esc), or by tapping anywhere on the screen on tablets and smartphones.
You can hit big Nikochans just like normal Nikochans, but if you press two keys at the same time or tap with two fingers, you will get more score than usual.
The more Nikochans you hit in a row without missing, the more Chain bonus points you get, and the more score you get.
On iOS, bugs in browsers (including browsers other than Safari) can cause taps with two or more fingers to go unresponsive. Falling Nikochan predicts this under certain conditions and compensates for it. If a tap goes unresponsive and the note is skipped, the chain continues without being marked as a miss. (This is enabled by default, but can be disabled.)
- This compensation is not 100% accurate, and some notes may be marked as misses, or in rare cases, notes that were not tapped may be respond.
- Also, since tap sounds are not compensated for, they are turned off when this compensation is enabled.