G-man man is asking you for another mission at Xen, this game is kinda difficult until you realise it. =P
I used to buy a "Half-Life Generation" pack and this was on the Counter-Strike cd. First I thought this is an original Half-Life expansion. The feeling is almost like in the original HL, sometimes more twisted. I loved the new places which werent in the original HL, for example snowy mountains or amusement park.
Summary: It's like an original Half-Life with some fun stuff, maybe a little longer than Half-Life. Everyone who loved the HL1 campaign should give a try on this! :)