Just like the article read, Resident Evil 4 and Resident Evil: UC did well because its basically a household name around gamers. Most gamers know what Resident Evil is. Especially now since their have been 3 movies about it.
Btw ide say more than 60% know about Halo. Even my mom who only watches Lifetime, HGTV and Univision,(yea the spanish channel) knows Halo exist.