I can't help but notice the screens for moonchild have the same textures as cave story. Are they open source or did the author simply steal them?They're not the same. It appears that they are just heavily inspired by Cave Story's textures. It's the same story with The Underside, which has textures that lots of people assumed were stolen. The guy who made that made the textures from scratch, but the game was supposed to resemble Cave Story.
http://www.gametrailers.com/video/angry-video-screwattack/65116I love this video, it's practically the wet dream of AVGN fans. Very extensive and thorough.