The phrase "party titles" refers to the names or positions that people have within a political party. It indicates the roles and responsibilities they have and helps define their position within the party's structure. Full definition
There are a number of first party titles releasing along with the console. (thetech52.com)
On the PS4 we'll likely see tighter performance and image quality on third party titles with first / second party pulling away considerably by the time the second generation of software hits. (sonyrumors.net)
On top of those 1st - party games came some of the best 3rd party titles of the year. (heavy.com)