It's important to follow the instructions written below the review under
The drag 'n drop method must be used exactly as instructed.
If you choose to otherwise do the mounting by yourself, read carefully the rest of the instructions, and specially note that (just like many other ones) the game must find itself every time at the same path where it was installed ("C:\DAGGER\" unless you re-install it at a different path). If your mount command is different, the game will crash to the command prompt, complaining that something was "not found". (You must understand the
dichotomy between the real paths in you OS and the virtual paths in DOSBox.)