Please note - this is to help you not waste months of your time developing something only to receive a Cease & Desist letter. This is just advice - but its a good idea if you take it.
RULES FOR CRYENGINE IP USAGE
- You are not legally allowed to import Crysis assets into the FarCry Editor.
- All Crysis IP rights belong to EA, however, you are allowed to use Crysis assets with the CryEngine 2's Crysis, Crysis: Warhead and Crysis Wars SDK only.
- All FarCry assets belong to Ubisoft and as such may not be used within the Crysis Editor.
SHORTLIST OF IP'S NOT TO TOUCH
- Mods based upon ANY Marvel franchise
- Alien/Predator mods
- Star Wars mods featuring the Jedi/Sith powers
- Square Enix
- Mods based on any Hasbro franchise
The main problem is that companies can perceive a modification on their Intellectual Property to be harmful to them - it may harm their sales, or may harm their appearance as two examples, hence why some companies won't let you do it at all.
RULES FOR MICROSOFT IP USAGE:
- Microsoft is slightly more lax about the usage of its IP - yet you have to follow certain rules to be able to do so. You can read the rules of usage in this post, here.
RULES FOR GAMES WORKSHOP IP USAGE:
- Like Microsoft, Games Workshop is more than happy to let people use its IP, as long as its rules are followed - disobey them at your peril! You can find them in this post.
(Thanks to MWLL|Death_Grin for finding those, and correcting my original post.)
RULES FOR AUDIO/MUSIC USAGE:
- If you want to use an artists' music, then you need to contact them first. Obviously, this is a lot easier if its an independent artist than someone whose been signed.
- Most of the time, artists will be fine with you using their music, but you really should ask before doing so.
GOOD RULES TO FOLLOW:
- Most companies don't like clones made of their work on another engine - particularly if they have the possibility to be better than their own work, and its free to access.
- You're better off asking permission if it is using someones IP, than just not bothering - perhaps they will say yes to you using their work, if you present it as not showing any kind of threat to their work, or a cause of loss of income to their work. They might even offer you work if you've done a good enough job!
- You're always better coming up with your own IP than copying someone elses. Remember - An idea cannot be copyrighted ("surviving in a post-apocalyptic wasteland, with mutants, slavers, and raiders constantly attacking you" is an idea). An expression of that idea (Fallout 3) CAN be copyrighted.
If you have any suggestions to add to this, that I may have missed, please post and I'll edit this post to reflect that.
Update: 2010 December. Added some information on music/audio usage.
Update: 2010 August. Added information on FarCry/Crysis/EA/Ubisoft/Crytek.