About this game
How to read the treble clef
The treble clef is the top staff in piano music, usually played by the right hand. The lines, bottom to top, are E, G, B, D, F. The spaces are F, A, C, E, which spell "face", so that one's easy.
Middle C sits on a little ledger line just under the staff. Above the top line, G and A hang off ledger lines going up.
How to practise it
Counting up from the bottom line every time is slow, so don't. Pick a few landmarks instead: middle C, the G on the second line, the F on the top line. Read everything else as a step or a skip from the nearest one.
A minute a day beats one long session. That's why a round here is 60 seconds.