not very sure what "not more than 50% obscured" mean because here's some examples which may similar to your opinion:
1: from
t/51905it's obviously 50%+ invisible, but a classicle style, and easy to read out.
2. from
this map, Insane diff, 00:10:327 (5) -
apparently, over 50% of its square is hidden by itself.
3. from
this map, Insane diff, 01:52:739 (3) -
1/3 square is hidden by prev notes, and approx another 1/4 square invisible for it's curved, (Easy to caculate by integral, won't list whole step here).
4. form
this map, Insane diff, 01:15:920 (3) -
over 50% square is overlapped by prev notes.
5. from
this map, Hard diff, 00:38:586 (1) -
over 50% invisible for prev score burst.
6. from
this map, Another diff, 00:32:475 (2) -
overlapped by both score and prev slidertrack
7. from
this map, Another diff, 00:15:576 (11) -
slider in stream which is hidden for score and prev objects.
and some other cases, including both self-overlap or overlapped by other objects.
all of these cases are rankable and playable now.