E-Z Dungeons Caverns of Chaos Fat Dragon Games is a redux of the existing E-Z Dungeons Caverns Basic Set.
The most immediately obvious improvement in this new set is its textures. Fat Dragon's textures have come a long way since the earlier set was released. The original textures were essentially a mottled, vaguely granite-like grey stone throughout, whereas the Caverns of Chaos feature gorgeous limestone stalagmites and stalactites on the walls pieces, and floor tiles with one inch squares subtly portrayed in the form of eroded stone.
The Caverns of Chaos features a number of new items. There is a large raised area and number of small ones. The tipsy and, in my opinion, largely useless narrow, triangular stalagmites of the old set have been replaced with attractive and usable large and small 2.5D stalagmites. There is an impressive lava fall along with modular lava rivers and modular pools of water. There is also a huge dragon skeleton tile. Best new item, in my opinion, is a stone bridge with a removable center span. The ramp of the bridge features a new non-slip system that prevents minis from sliding on the slanted surface.
A few items from the older set do not appear in the new version. The mining rail tracks and cart, the rope bridge and the giant the mushrooms are gone. I wasn't sorry to see these go, though, as I never used them.
The geometry of the wall pieces of the Caverns of Chaos is identical to the old set, which is more polyhedral than the boxy shapes that characterize walls of the E-Z Dungeons dungeon sets. As a result the Cavern pieces are more difficult and significantly more time consuming to build.