Micromegas: I don't know, but there are actually 5 maps. I'm guessing each one for a different piece of armor (haven't tried to search for them yet).
Each of them is for a diffrent chest, each chest contains various loot including pieces of the Warhorse armor (named after the studio but for the player not their horse).
I have the DLC but I certainly hope it'll be made avalible for sale.
People who didn't hear about the game right away, people who would rather play on GOG but were backers so started out on steam, and people like me who'd like to support the game buy giving it as a gift to others (but would really like to offer the full exprience), would all welcome the option to buy the DLC so it seems like a win-win to me.
