Citadel episode was good. But I understood half of it. What the fuck *actually* was the curve? What was Evil Morty's plan and where the fuck did he go?
I don't know if I feel dumb for not getting it, or if I feel they're trying to make the show sound smarter that it really is.
From what I got, the finite curve was a linked collection of the universe's the portal gun CAN travel to, but due to the overall Rick's ego, these universe's are where Rick is always on "top".
Evil Morty wanted to break that cycle by luring all the current Rick's to the citadel where their portal guns would become corrupted. That's why he was waiting for "our" Rick to get there as he's considered the smartest. Once the plan was activated to kill all the Rick and Mortys, Evil Morty then set to destroy the curve.
By destroying the curve the universe "lock" was lifted, the portal gun could access ranges outside of the curve. Evil Morty travelled outside of the curve and once he was in a new universe decided to activate the portal gun, which created a new yellow/gold portal.