It's... more Vampire Survivors. Although, I have to say, I don't like these new maps as much -- the second map is a bit annoying and the methods for unlocking the next steps in the DLC are rather roundabout, even for VS standards. The new characters are pretty satisfying, though -- it's impressive how there's still room for new ideas when the game has so much stuff in it already.

Side note, but curiously, because this DLC introduced extremely efficient gold and golden egg farming methods, I found out that people grind in Vampire Survivors. Why? I know many of the crappy clones (especially F2P ones) force people to do so, but in the original VS, I never had or felt the need to -- it's why I liked the game so much. It was a confounding discovery.