The two rules of this cube...

1. Cycling should be a central mechanic
2. Be playable (and affordable) on MTGO

So, what decks do veterans think of when you say "cycling"? Astral Slide (now Astral Drift); Life from the Loam with the cycling lands; cycling into a cascaded Living End; Ikoria's RW aggro; even New Perspectives combo. Plus there's all sorts of graveyard shenanigans, "whenever draw" and "whenever discard" triggers to have fun with.

This cube attempts to pull all of that together.
It's still in the experimentation phase, including the following questions...

• What's the right power level? Both overall and for the cycling cards themselves? Besides landcyclers, ideally they should all be castable as well.
• How big a role cycling can/should play. With too many payoffs, it can be the correct draft strategy to just take every cycling card you can and rely on your 5-7 key cards.
• How does the amount of cycling affect deck consistency? Do you need more playables since the land count is lower? Can you have more themes across colors since you just cycle into those specific interactions more often?
• How big should the cube be? 360 is a good start to figure out the focus and what works, but it might also be the end result if I'm already doubling up on some cycling cards/payoffs to keep power level more consistent.
• ...and more...

Here's where things loosely stand right now as far as decks & color themes:
WU - historic; astral/protocol; enchantments
UB - self-mill
BR - cast from graveyard
RG - Cascade Aggro
GW - Threshold Aggro
WB - Zombies; ETB/Blink (note that it works with unearth abilities)
BG - Spider Spawning; GY recursion
GU - Cascade value/combo
UR - Looting
RW - Fox Aggro

This is very loose, and I imagine it's easy to end up 3+ colors with both the fixing and consistency from cycling. For instance, you could make Astral Drift/Escape Protocol loops work in just about any color combination you can imagine; Black has reanimation spells in each other color; etc.

In any case, feedback is welcome. As I said, still a lot of open questions here.