Oa Central Battery

Real nice !
I loved this stage, that I was using as GL stage for one of my games, but always with the sadness that they were (as intented) quite simple, lacking something.
I can't test it for now, but I'm sure it is great, and I hope you will continue this process

Ok, I checked the stage (finally !), and I really like the result (especially those green construct robot, like those in O'Ilu's Justice League game, real nice)
2 points to upgrade a bit the thing IMO (don't worry, really easy to make):
- you should change the background color a bit. It's a bit too yellow for a GL stage . A darker (or lighter) shade of green might look better.
- you should animate the background a bit. It's kinda still and gives too much attention to the rest like the robot, that should be a detail and not a point of focus.
2 options here (that can be combined):

• there are spotlights in the background, but they are still. Either remove them or move them. Luckily, your background is all black, so erasing and/or replacing will be easy. You can either anim it by slightly making it blink or change tone, or go full on changing by adding some new spotlights, like the one in Styder's stage from MvC, or even from the Casino Zone of the Sonic Games. It should not be hard at all.
  
• animate the buildings, either by adding blinking lights, like windows, or even changing slowly the shade of the color, to give the whole thing a "blinking light"/ "living light construct" kind of vibe
  

All of this should bring a bit more life to your stage.
But it's overall really good, and I'm definitely gonna keep it