Akumajou Dracula X: Gekka no Yasoukyoku (Saturn)

A Japanese-exclusive port of Castlevania: Symphony of the Night with several extras, but it suffers from shoddy porting quality.

Hidden Files
If you try opening the game's disc on a PC, you'll be able to find several files not accessible while playing the game.

Art Files
There are also 15 art files included that are not accessible in the game.