Why is the Warehouse level SO dark?
I'm (trying to) play Spiderman (2002) on my GameCube, but it's so dark I can't see anything. I'm using an AV to HDMI adapter that you can see in a photo in the comments so I don't know if this is the issue or not. Can someone help? Thanks in advance.
This is a common issue with those cheap adapters. Either use a better adapter or scaler, use composite/component, or look into one of the gcvideo based solutions for a native HDMI port.
Sounds like your black level settings aren't correct.
See if you have a limited vs full setting in your TVs advanced options.
Sometimes it's called "black level" depending on the model.