This may be a random way to start this, but Elevator Passes are extremely helpful and empowering. Mine just expired the other day and the lack of freedom is crippling right now, but it has given me a lot of ideas and opinions about the Arcade, Energy, and the Pass.
Passes allow players to make more money, but can lead to people playing far too much, something the Energy system is meant to prevent. Still having that ability to exceed the play limit and give yourself a little bit more energy without using precious CE is something that I feel would be a welcomed addition to the game. To keep that feel of having a limit, this implement needs to be something that you can't get very easily. Something else I feel it should do is bring back some use to the Arcade and the various Minerals we collect.

Use the Minerals we collect and deposit into the Arcade eventually give a reward of a Mist Tank.
This can be done in a few different ways.
- Every time a player eventually deposits 500 of each Mineral into the Arcade, they get a Mist Tank as a reward for their work. (Just a test number for now. Could be more than that.)
- Every time a player deposits Minerals into the Arcade, they get some "rejects" as Materials. These new materials can be crafted together to make the Mist Tanks. The bigger Mist Tanks would take more materials and actual Energy to craft.
- I'll add more here if you guys can come up with some.

These Mist Tanks would be unbound and be able to be sold on the Auction House, allowing for players who have Elevator Passes, as well as other players who have no need for the Mist Tanks, to have another source of income. Having that option of getting a little bit more energy is something I think is too good to pass up for OOO. The limited Energy system, as great as it is, does push away some players. Giving them the option to be able to play longer if they work for it aside from burning that valuable CE would be a great idea.

Now, to avoid people spamming that sell all button like they always have been, maybe set goals or benefits of some sort for actually working toward a new Stratum type. If someone hits sell all, it goes into the elevators evenly across, filling up an invisible drop box until all mineral numbers are even. This was you don't get someone randomly selling stuff messing up a stratum that other people are working towards. Which leads me into my next suggestion.

Elevators generate specific "secrets" that hint at special Strata that Knights can create
Another idea is to have that Knight who has that pet blue Jelly that you sometimes see in the Clockworks say, "A Stratum of this type on Stratum # would yield some interesting finds...," and if that stratum were to be created where he specified, something special might be waiting there in the level rotations. It doesn't just have to be from that one Knight either. There could be some Owlite tomes that mentions various stratums in the Candlestick Keeps. A Almirian tombstone that mentions another stratum in Graveyards. Those mysterious statues in Aurora Gardens could give another. Hell, make a Tortodrone be guarding a secret!
This opens up a TON of possibilities for level design and may even introduce a new way for Boss stratum to be generated, allowing for more than the 4 bosses that we have now for each elevator. We could seriously CREATE our own bosses and Clockworks. To help facilitate this, add a message board of some type where Knights can report their Clockworks finds in the Arcade. It would just be a simple fill in the blank type of thing for each elevator, saying what secrets were found and where, that Knights can report in for a reward. This gives the people who want to create a specific stratum type to have a reference and to make a little bit more interaction and exploration between the players.

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Well, those are my thoughts. Sorry for another long-winded post, but that's how I am. Let me know what you guys think and if you have any ideas to suggest along with this. If you disagree with something about it, help me out by doing more than saying "No this won't work." Please say why, hell, even suggest your own version that would work!