Fresh pickups, nastier enemies and new bosses give the basement loop a good shake-up, while the added challenges leave plenty of room for experimenting. A single item can still throw an entire run sideways, which is half the fun when strange combinations start clicking together. The full version is unlocked.
The extra content blends into the existing runs instead of feeling bolted on from the outside. It is a solid excuse to start another run, test odd item pairings and see how far a familiar build can be pushed.