IIDX 7th has "Masters Mode", it's like a quest mode, kinda. All home Bemani need these, I think.
So, you get one lifebar, and you have to pass every (pre-unlock I think) song with that one lifebar. It builds back up really slowly, like in expert (nonstop/ranking, you know) mode. You choose which song to play as you go, and you can change the options. Also, as you beat a bunch of songs, you can gain meter capacity - I think right now I've got 2/3 of the songs done and I have like 200% meter, and that might be where it tops out.
I hear that if you fail (I haven't yet), you get to start over with a 'potion' that you can use once to refill your meter, and another one every time you fail.
Also, there's a big fat prize for finishing.