Yeah, but you have to think, HL is a classic, and the fact that there's only one hero is massively significant to the plot. That'd be like Ash having six Pikachu.
I'd be honored to co-own it, but I'll need to do a lot of reviewing of my Half-Life lore to get everything straight, Poke-fy it, and find a good scenario.
Couple examples: Scientists and security hole up in the Lambda complex until Freeman arrives. The players could be the survivors here, holding off the aliens until something happens.
A large team goes to the alien world, though they ultimately die. We could do a variation of that, of a team that travels to the alien world to try and close the portal from teh other side.
From the perspetive of some of the soldiers sent in.
Those are just a few ideas.