Today, I've got an e-mail from Marie-Laure Ryan saying she is very excited about my paper Computer Game Criticism, because each level puts the study of computer games in a different context:

Layers 1 and 2, computer applications; computer science.
Layer 3: Cybertext theory (a context that includes hypertext, e-mail, blogs, whatever).
Layer 4: Game theory and ludology (the Caillois, Huizinga, etc. tradition)
Layer 5: Narrative (not just literature but myth, legends, history)
Layer 6: All cultural representations, including art.
Layer 7: Human behavior.

You may find the paper along other papers in CGDC Conference Proceedings which by the way Bryan-Mitchell Young lately reviewed very positive: Basically, this is the best "book" on videogames published to date. It's not available in bookstores, but I highly recommend you get it.