In his latest newsletter email, Dave Gilbert announced that all Blackwell games are now available on Steam, and at 25% off. If you previously purchased a game email him with proof for a free Steam voucher. He'll also be giving away some vouchers through Twitter this afternoon.
The Steam versions have achievements and a new commentary.
Adventure Game: Broken Age
Casual: Redemption Cemetery: One Foot In The Grave
Darkside: The Witcher