Kleiner wants to destroy the Borealis and its technology completely.
The Resistance under Magnusson wants to take Borealis technology and use it against the Combine.
Gambit Pileup: Each sentient faction has their own intentions for the Borealis.
Driver Faces Passenger: A rebel piloting a shuttle with Gordon in it hits a strider on accident when the rebel was talking to Gordon.
Demoted to Extra: Alyx mainly stays in a house mourning Eli for most of the game.
Death by Looking Up: Several fast headcrabs attempt to do this to Gordon within Kraken Base.
Kleiner actively hidners Gordon's progress and tries to blow him up when Gordon arrives at the Borealis. He is clearly crazy but docile in City 18.
Breen also makes a return, but he doesn't last long.
He can potentially die at the end if the player opts to save Alyx over him. He makes another appearance when the Resistance takes the Borealis technology.
The Bus Came Back: Barney returns in this mod, initially in City 18.
The war has escalated so much that there are no citizens in the city anymore and the Combine have orders to shoot any non-Overwatch unit on sight.
Bug War: City 18 is in the middle of one between the Combine and Antlions due to a massive hive near the city.
Bigger on the Inside: The Borealis's interior is considerably bigger than its exterior.