Recap up to the end on Hl2:Ep2 and then a Gman scene?
Like "Well, thisssss is, Unfortunate. But he was warned to prepare for unforeseen consequences. Now, Mr freeeeman, my employers would like to,... congratulate you on your success so far, and the amount... of effort you have put in... but your job is not finished. Not yet."
Sad flight to Dr Mossman?
Arrive and land, helicopter blown up on the landing pad by avalanche, falling ice or building collapse?
Start with only a crowbar???!!!!
Have one of the cut air-plants, where remaining combine are massing?