The ending of HL1 is simple. You kill the big foetus-looking thing, then you get teleported in some room by the G-man.
He explains to you that you were stripped of your weapons and such. Then he proceeds to say you have big "potential" and that it should be exploited. He gives you the choice to enter a portal and accept working for him, or die.
When you enter the portal, you get a screen saying "Name : Gordon Freeman, Status : Employed, awaiting work" or something like that, don't remember the exact thing.
But yeah, the ending didn't suddenly make me understand the whole story.
Oh and so I don't hijack the thread, my goal is to do 1 level a day, and I'm level 33, sooo being level 38 by Sunday is my goal, and hopefully have a good chunk of money saved up for my cuddly little panther.