The Perfect Dark GlitchCassandra out in the cold.
If you want, you can turn on cheat "Marquees of Queensbury Rules" to make things easier, but on Level 3, Datadyne Extraction (Preferably on Perfect), you AND Dr. Caroll can't get hit by any of the guards on the ground level.
Kill them all, make your way up on the avaliable lift and you'll turn the corner and see a guard you don't usually see. Kill him, take his keycard... complete the level up to Cassandra and the bodyguards and get Cassandra to leave the room. Then go down back to the ground level...
Go the the room with the computers and stuff in it in the first level (where you attach the Comms Device) and you'll see Blonde and the 2 guards in the cutscene for the end... and Cassandra behind Blonde...
What you have to do is get Cassandra to follow you by moving from side to side whilst going backwards. She ends up following you and you can take her outside the DataDyne building (yes that keycard unlocks that door) and leave her in the cold.
Most of you have prob already figured this out but I still thought I'd say it. I love Perfect Dark and hate Halo
Eli.