Here's a relatively fresh one for you! A few months ago I started a project with a programmer/developer. It was to be called "First Realm".
The concept was relatively simple as far as multiplayer online games go. Characters would traverse an idillic landscape free of any danger. However, in order to attain Gold and Items and all that crap, you'd have to dig...
dig into procedurally generated dungeons!
Pictured here: Anonymous hook-ups.Other players would be able to come down into the dungeons with you, where you'd face a Gauntlet (classic arcade game) styled battle against hordes of weirdies. The first level you dug would be relatively simple with a low pay-off. Then, you'd be able to dig futher... and further... and further... each level getting increasingly difficult.
In the end, the programmer I was dealing with spent those few months doing nothing on the project. (As far as I know.) He wanted to converse via Skype, so I downloaded and installed it, then he was rarely on when I was. We spoke a few times, but during the last conversation I asked what had been done and he said he no longer had the free time.
Oh, well.
At least I have the defunct design ideas and a bunch of useless artwork for my troubles.

Artwork I've shown to several developers since then, all of whom don't like it.
Buttever! Here's the sprite sheet I had so far at the time of fall-apart...
Click to enlarge. Or don't.I guess I shouldn't have bought FirstRelam.com, huh?