Just a month before it was set to go live, Endless Dungeon developer Amplitude Studios has decided that "there's still more work for us to do," and so it's delayed the release to October 19.
"This will give us more time to incorporate community feedback and make the game as great as it can be," the studio said. "During this extra time, we'll be working on meta-progression, balancing, in-game economy, as well as loads of general polishing and bug-fixing.