If you suddenly notice your Roblox game screen appears completely green, this means you likely have "Green Screen Mode" enabled in the Roblox camera settings. This makes the game environment green so that you can record footage of just your avatar isolated from the background. The green allows you to remove the background later using chroma key compositing tools and overlay anything behind your avatar. Disable green screen mode in camera settings when you want to return to normal gameplay with the default environments visible.