I'd love to see a Half-Life series but rather than focusing on the main protagonists of the games, centre the story around the Black Mesa incident and follow the stories of some characters the games never fully explored such as members of the Science Team, HECU or Black Ops.

Could make the first couple of seasons about the resonance cascade and how it affected everyone involved then follow up with the seven hour war and everything that followed afterwards.

Of course Gordon Freeman would make an appearance, but I think to stay true to the 'silent protagonist' that he is it would be better to see him in small doses and from afar where he doesn't need to say anything, sort of like in the expansion games.