It's Bubble Bobble, and not much more. The game does a terrible job of explaining where its content is. "Hard Mode" is where the extra levels are, and Hard Mode's arcade is where the challenge tower is. The game does not explain that, and therefore appears shorter than it is, much like Dariusburst.

Dunno why this is a separate game on here when it's really a free update that adds onto Bubble Bobble 4 Friends, hm.

Anyways, with the new content I think it's more worth the price. It's difficult, but then again that's the entire point of the Baron is Back mode. Still would wait until it's $30 or lower, but they at least addressed the criticisms of it being too expensive for what the base game offers.