http://www.gamesas.com/topic/1331715-unofficial-steamdrm-discussion-26/

Copy paste from my just submitted Steam Support Ticket
I am having trouble with Avadon:The Black Fortress.
I played the game for 15 minutes last night (Sunday 3/11). When I tried to play today (Monday 3/12) I got the message that the game was currently unavailable, try again later.
I tried to Validate Game Cache but instead I accidentally deleted the Local Content. Now I cannot download the game, I get the message that the Steam servers are busy. While troubleshooting I downloaded 2 other games and updated the Steam client twice, so I don't think it is a busy server problem.
I did try most of the steps here:https://support.steampowered.com/kb_article.php?ref=4595-WEXN-6831, but with the game not installed I obviously couldn't try them all. None of them helped.
I played the game for 15 minutes last night (Sunday 3/11). When I tried to play today (Monday 3/12) I got the message that the game was currently unavailable, try again later.
I tried to Validate Game Cache but instead I accidentally deleted the Local Content. Now I cannot download the game, I get the message that the Steam servers are busy. While troubleshooting I downloaded 2 other games and updated the Steam client twice, so I don't think it is a busy server problem.
I did try most of the steps here:https://support.steampowered.com/kb_article.php?ref=4595-WEXN-6831, but with the game not installed I obviously couldn't try them all. None of them helped.
Anyone come across anything like this before? Nothing had changed in my PC setup or programs since the game worked last night.