Look like v1.1.18 fixed the "full clear" stamp. The maximum score is now 365. And when you get a full clear you get an ominous poem, which ends with a suspiciously purple question mark. I wonder if it's yet another hint...
Interestingly I tried a run without a full clear and still got that ominous poem. Perhaps it's just level-based. In that run I left both gazers alive which had no special effect.
