It will run more than fine, as it is quite an old game. I can even run games from 2010 on my 2009 MBP. Thus you should be able to run a game from 2007 or 2003 (?) on an MBP from 2011.
Or is that some special version of Halo you are talking about?
Wirelessly posted (Mozilla/5.0 (iPhone; CPU iPhone OS 5_0 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A334 Safari/7534.48.3)
What version of Halo do you have? In 2006 there was an update to 2.0.4 and it is an Universal Binary, thus it runs on Intel Macs without the need of Rosetta. http://www.macupdate.com/app/mac/13886/halo