V Rising

Dracula's Castle is located on the rightmost part of the map in the middle. To get there, you first need to build a "Craftsman's Table" (Production - Crafts tab - Craftsman's Table) and then inside craft the very last thing, the "Bloody Key"

The easiest way is to create a world with the maximum initial level of equipment and easy difficulty, + remove the required resources for construction to zero, otherwise it will all take a very, very long time...