According to Wikipedia’s article on Video Game Development Parties, a first-party game developer is a game developer that is part of a video game hardware development company, and that develops games exclusively for that company. This term typically refers to developers of one of the three hardware giants, Nintendo, Sony, or Microsoft.
Examples of usage:
· “Did you see the first party updates at E3? Nintendo definitely had the best presentation.”
· “Microsoft uses a large number of first-party developers that make games for the Xbox 360.”
References: http://en.wikipedia.org/wiki/Video_game_development_party. Retrieved on 6/25/2012.