When I bought the Orange Box it was like 85% for Portal and 15% for Team Fortress 2. GLaDOS is one of the best video game villains ever.
Spoiler (Highlight to read):
"Didn't we have some fun though? Remember when the platform was sliding into the fire pit and I said 'Goodbye' and you were like 'NO WAY!' and then I was all 'We pretended we were going to murder you'? That was great!"
Also: This was a triumph....