So you know how some depths show a mystery symbol and a series of possible levels? This has made me think of a new concept: "Empty" depths. The elevator before these depths (maybe always at the very end of an arena?) will contain a mineral box. By depositing minerals in the box, you influence the chance of getting a certain level, much like old gate construction. However, there will always be a chance of a random depth being selected. Now, the way this works is that there will be an arsenal besides the elevator, but no arsenal on the following level, whatever it may be. It provides a bit of a challenge in that you may end up with some really anti-current gear levels (inb4 Acheron, Nitronome, Skolver FTW since even that has some difficulty on compounds). Let's say that every mineral added adds a 1% chance for that level, up to 99%. And providing enough of different minerals raises the chance of a "special" level (TV, graveyard, danger room, scenario room, etc.)