First, there was Brinstar.
Then, there was Brinstar Depths.
Then we had Norfair.
So what comes next? Why, logically...
NORFAIR DEPTHS!!
(Otherwise known as "Ridley's Hideout")
Name: Norfair Depths
Game: Metroid (NES)
Description:
As I'm sure you know, the black lines indicate where you can stand, with the pillars being impassable. Also, any platform with a black line on it cannot be passed through from any direction. See that fancy new WHITE line? THAT one you can pass through.
As you can see, the stage as a fairly asymmetric layout, and lots of curved/slanted platforms. To some, this may seem like a detriment. But then the gimmick comes into play. Now, Norfair is known for the intense heat and lava. So what do you get when you enter an area directly below one that's flooded with lava?
If you guessed "Lava flows", you're correct!
Yes, after a random amount of time (with a minimum of 30 seconds), a message will appear at the top of the screen, warning of "Dangerous Heat Levels." When you see this, get to a safe place, because the lava will soon after start flowing down the level, as shown in the above image. The lava acts much like the acid in Brinstar if it is touched. You'll get fair knockback, and some damage. After about 10 seconds, the lava will stop flowing.
I'm not going to touch on aesthetics, for fear of demoting a long hoped for character to background status. Just imagine a mix of the "Norfair" and "Brinstar Depths" backgrounds, and you'll be pretty close to what I imagine.
Unlockable?: Yes. Play 10 rounds on Pyrosphere to unlock.
Music:
Norfair Depths (Metroid)
Space Pirate Theme (Super Metroid)
Underground Depths (Super Metroid)
Ridley Battle (Any game, they're all the same theme anyways)
Mother Brain Battle (Super Metroid)
Magmoor Caverns Ambience (Metroid Prime)
Metroid Prime Final Boss Theme (Metroid Prime) (Duh)
There you are, my Metroid Stage! Hope you like it!
EDIT: I'm suddenly a bit paranoid that you won't quite get what I mean by the platforms that can't be passed through, so here's another pic of the stage, with black lines on any ground, wall, or ceiling that you cannot pass through.
It was probably clear enough the first time, but like I said, I'm paranoid.