Super Mario XP
From Mario Fan Games Galaxy Wiki
Super Mario XP is a fangame that was originally released in Japan by CNC Darkside. This game features music, gameplay mechanics, and a graphics style to match that of the early Castlevania titles. There are a total of eight memorable levels in this game; Seven of which having a unique boss at the end of each stage, and the last being a boss rush level. This game has been praised for its engaging level design and difficulty. One of the game's more notable aspects is that it rather successfully meshes together the classic Mario gameplay with various elements from the original (pre-SOTN) Castlevania games.