You can't trademark the word, but you can trademark the name of your game. Since someone else is using as their game's name, Blizz can't call their game the same thing. Take Halo for example. MS does not own the word "halo", but they own Halo as a game/comic/movie/TV series/ect. name and nobody else can make a game/movie/comic/ect. and name it Halo.
The amendment is necessary pursuant to a separate co-existence agreement entered into by the applicant and a third- party. The party has indicated an intent to challenge the description of goods/services as originally filed by the applicant, unless the applicant makes the proposed amendment to the category description. The proposed amendment is within the scope of the original filing, and includes discreet language modifications that will prevent customer confusion between the marks.