As far as I know, the only version of Alpha Protocol, that activates on Steam, is the one from Green Man Gaming. Seems like they have a special agreement with SEGA to get Steam keys for a couple of their non-Steamworks games (others are Medieval: Total War and Rome: Total)
https://support.steampowered.com/kb_article.php?s=b893c194a77776946fb13dbd87d93956&ref=7480-WUSF-3601 doesn’t look like it.
Doesn’t, because it’s not in this list: https://support.steampowered.com/kb_article.php?ref=7480-wusf-3601
As far as I know, the only version of Alpha Protocol, that activates on Steam, is the one from Green Man Gaming. Seems like they have a special agreement with SEGA to get Steam keys for a couple of their non-Steamworks games (others are Medieval: Total War and Rome: Total)
That list has never been complete.