From Destructoid: “On September 13, A Hat in Time will be supplemented with an add-on called Seal the Deal. This DLC chapter takes place on an arctic cruise, has six new time rifts, and introduces a tougher difficulty mode called Death Wish. Also, there’s a stupidly cute seal; it’s in the gallery of new screenshots at the bottom of this post.”
Source: N4G PC A Hat in Time gets free story DLC and a cooperative mode in September