Lissar said:No excuses on Gray Matter and the Black Mirror series! Though actually I have physical editions so I can't complain (and I don't really blame Valve for it since I don't know what the situation is. It could be the publisher stalling or just not wanting them on Steam. I have no idea so I can't pass judgment. I just find it exceedingly curious.)
I don't think Valve has anything against adventure games in particular, from what I've heard the discussion is usually about the price point.