Seems all Doom games are on sale if you don't have one of them yet lol. Even Doom 2016 is 50% off right now

Doom classic Complete: http://steamproxy.net/steamstore/sub/18397/

http://steamproxy.net/steamstore/app/2280/

http://steamproxy.net/steamstore/app/2300/

http://steamproxy.net/steamstore/app/9160/

http://steamproxy.net/steamstore/app/2290/

http://steamproxy.net/steamstore/app/208200/

Doom 3 and Doom 3 pack

http://steamproxy.net/steamstore/app/9050/

http://steamproxy.net/steamstore/app/379720/