Package halflife-steam has a confusing name and description. First of all, for the name, 'steam' should be better as halflife has no direct relation with steam. Steam is a Valve product and it just helps to install games. Half-Life is only one of those games. The worst confusing thing is the description of the package. It is "client for Valve Software's Steam content delivery program". As halflife-steam package is in games-server and as there is only a linux version of the steam server, I think writing "client" in the description is realy confusion. To have steam client, we must use wine or cedega.
It's clearly a client for the content delivery program and it's the halflife server delivered via steam. You're the only one it's confused in the 5 years it's been in portage so we'll keep it the way it is.