Do I need to post a bigger picture? How long should I wait to do so?
Pacing is entirely up to you. If you don't see any action in the thread after _______ units of time, you are free to enlarge. You can be conservative, opting to provide several clues over a short period of time...little by little.

Or dump 1/3 of the screenshot in you next post.
It's all good.
Now I think it might be an underwater temple from a Darius game.
Final Answer:
"Darius"