Hmm… just looked it up, apparently there’s a level 30 cap, but you can get some upgrades from Fortune Teller side quests (from a reddit post). Have you done all of those?
Never heard of Antichamber before, maybe because it’s PC only. Went to steam to wishlist it for future, but it turns out it’s already in my library, and it’s old enough that it’s possible my system can run it. Will give it try.