Hey there Anzan...try these links.

The first one is Blizzard's site...you can also check other game developer's sites for their requirements.
Blizzard's Submission Requirements

Look for post by mythwarden further down...don't know what company he/she works for but this is what they require.
Forum thread

This site is a 3d Forum...CG Talk

This next one is mainly a forum for concept artists but I believe some of them have worked or work for a gaming company...they may be able to shed some light on some things for you as well...
TeamGT