The Magnussen Device doesn't make sense.

[McGooTheWise]

Yes, but in order to get to the button, Gordon has to go through a legion of combine troops, by himself, with no aid, because Alyx is in emotional distress, Eli is dead, D0g is taking a shit on the lawn, and Magnusson, for some strange reason HAS to taunt you the entire way, or you won't get there.

 

[goremanfreed]

Well they kill striders faster than rockets. Combine would have easily destroyded White forest if they sent all of their forces to it. Of course they didn't know about the strider buster device.