Has some decent advice on atmosphere but since the engine is limited you can't do much. Try to make the environment darker in both of your games to atleast have some sense of atmosphere. Here's a pixelation shader if that'll work for you:
Check out post processing if CC6 has that. Also consider switching to Unity at some point, it's free if you have the time to learn. <3
You should check out a tutorial for PSX shaders because it looks like you've got the default lighting on your games. You should put a low resolution effect on or something similar.
