After entering the Grave Pillar and attempting to ascend, Copen and co. encounter a large bulkhead blocking the way with two empty keyholes, one purple and the other yellow. After seeking out and forcefully acquiring the keys from two Gravekeepers, he and Lola tell the others to stay back while they head through first, not knowing what might be behind it.
The Grave Pillar stage that makes you realize the true shape of it. The Passage to Upper Stratum is a stage linking the blocks between themselves, and compared to the previous stages, the backgrounds and gimmicks become way simpler. The structure becomes more mechanical in feeling, a research facility tower; you can feel the original shape of the tower.[1]
