What floor are you on now when you go upstairs?
One up, one down, two ups and then two downs.
Now what floor are you on now?
Numerical ability and good memory are the key.
You got two modes to play with: one to take plenty of time, and the other to be originally a time trail, called "speedrun mode".
Both modes accept the world rankings.
-- How to Play
1. Momorise the current floor shown on screen
2. Figure out which floor you are now depending on the content of your action
3. Adjust the floor by up and down button and then push "Enter"
*During speedrun mode, you compete to see how faster you can get all 15 right answers. Even one mistake, the game ends.