So, I recently had an idea based on the old "beat the previous deck" game. In that game, you had to post a deck to beat the deck above you, and the game was over when the first deck posted could beat the most recent deck. In this variation, the goal is to have the thickest stack of decks you can. The restriction is that each deck must beat _every_ deck above it, and therefore must lose to _every_ deck below it. The normal PHM rules apply, and the defeat must be 6-0 in every case.
Pretty sure the stacks in this game can easily get to 100+. I started building one, but realized I could just start from a much worse, super elongated win-con and gain a ton of leverage that way.
Here are two example stacks for 3CB:
Plains / Island / Forest
Plains / Swamp / Abyssal Gatekeeper
Plains / Swamp / Aven Skirmisher
Plains / Forest / Azorius First-Wing
Mishra's Workshop / Ensnaring Bridge / Scalding Tongs
Hollow Trees / Reclamation Sage / Reclamation Sage
Plains / Plains / Plains
Forest / Forest / Mayor of Avabruck
The first stack is better than the second since there are 6 decks, as opposed to the second stack with only 2 decks.
How big of a stack can you make for 3CB? How about other formats? 1CB LR seems to be a reasonably solvable problem.
lotus petal / flailing soldier / evermind
arbor elf / forest / evermind
gut shot / island / fugitive wizard
gut shot / forest / elvish lookout
yotian soldier / ancient tomb / sol ring
mental misstep / plains / isamaru, hound of konda
mental misstep / dwarven hold / beacon of destruction
ensnaring bridge / chalice of life / mishra's workshop
hollow trees / beast within / elixir of immortality