[gold stinger]

Okay, so.


Considering that Rare contacted you back saying it is ok as long as you follow the Game Content Usage Rules, Based upon latest rendition from January 2015, this is a valid blanket permission for any and all Rare-associated game soundtracks and music owned by Microsoft, granted that FlashFlashRevolution stays non-profit. FFR may still accept donations, and generate income based on assets associated with FFR as long as it's not directly making the money off of the publicity of said song or artist. Since FFR is active in a way where there is more than 2000+ songs that drives its reputation, this shouldn't be an issue.


If for some reason there is ever a separate, approved downloadable version of the game that shy's away from the website and requires downloading the music separately along with the Game Content before playing the game (again, should not be an issue because the downloadable version of FFR has to connect to FFR to load music data) then this disclaimer must be included in the README for any songs regarding ownership via Microsoft:


"[Name of the Microsoft Game] © Microsoft Corporation. [The title of your Item] was created under Microsoft's "Game Content Usage Rules" using assets from [Name of the Microsoft Game], and it is not endorsed by or affiliated with Microsoft."


Outside of that, The legal perspective (but not quote for quote verbatim) is that "Microsoft grants a personal, non-exclusive, non-sublicenseable, non-transferable, revocable, limited license to use and display Game Content and to create derivative works based upon Microsoft-related and owned Game Content, strictly for personal or noncommercial use.


TL;DR this is blanket permission for Rare-related music owned by Microsoft. According to Usage Rules, there is blanket permission for Halo 3 soundtrack as well.
For anything else outside of that, contact the associated developers of the game first. If they tell you that it's all good as long as you follow the Game Content Usage Rules located on xbox.com, then that constitutes blanket permission for their associated works. If you cannot reach the associated developers of the game for some reason, then it falls under the legal perspective (but not quote for quote verbatim) listed above. If the associated developers respond and say no, then it's rejected.