While the Obsidian Tower game along with its first expansion pack (Uprise) is a challenging experience, this Expansion Pack has been designed for the staunch strategist who requires the ultimate test. This Expansion Pack is not intended to be a standalone game and must be added to the original Obsidian Tower game ideally along with its first expansion pack. Additional heroes join the battle and a new hybrid attack mechanic ensures that the difficulty of the game gets amped up a few notches. If you like the ultimate test, then The Obsidian Tower: Downfall is for you! —description from the publisher