Party goer achievement

[mr.chips]

Does anyone know how I can do the Party goer achievement.

 

[AciD]

Just complete game. WITH STEAM

 

[Omnomnick]

Its at the end of Test Chamber 19, just after GLaDOS says 'Assume the Party escourt submission position or you will miss the party' then launch yourself onto the platform that leads into the facility, then the achievement should pop up.

 

[Selkcip]

Shouldn't you finish the game before you go worrying about achievements?