I'm proud to announce you can now purchase Retro-Pixel Castles on itch.io and IndieGameStand. Both sites will come with a free Steam key, and a 100% DRM free copy of the game that you can launch without the Steam client.
If you're interested, you can find them both here:
http://rayvolution.itch.io/retropixelcastles
https://indiegamestand.com/store/1924/retro-pixel-castles/
They'll be 20% off on both sites until Tuesday. :)