In the tunnel between the chamber the warden's office you can go left to exit :)
SPOILER:
The Six-Handed gate wasn't meant for you - it's one only the other student who was with you can access. The fact that your character can see it at all is actually very unusual.
Oh, okay. Then I beat it. All 4(?) variations. I really enjoyed it.
SPOILER:
There are a couple of bugs/oversights. After dealing with Marcus and leaving the final room the door doesn't work and you have to walk into the corner just above it to leave the room and you can climb the shelf the Onyx Key was on after taking the key. Neither are game breaking so they aren't a big deal imo.
But I really enjoyed it. I'll be looking forward to whatever you release next.
PS - Were the Harvard phrases just there for vibes or are the interwoven into the narrative?