Where is Nexus Blitz at?

This was quite possibly my favorite game mode in all of LoL history.

Games no longer than 20 minutes. A fresh new map that still had lanes, but everything was in close proximity enough that everyone could roam and be everywhere at the same time. The random mini games built into the mode made every game have some variety. And winning, the game would end soon for you to start another Blitz. Or if you were losing, you're never that mad because the game can be no longer than 20 minutes, so you're never held hostage. And even when losing, you always had that "last chance" opportunity to come back if you made it to the 19 minute mark.

It was such a fun and simple mode, but it vanished right as I thought I heard word of it becoming a new permanent mode down the line? Anyone know if it's still in development? Or if they still plan for it to be permanent?