SUPER MARIO XP / CnC Darkside / PC
Are you familiar with the concept of "mash-ups"? This is when someone takes two (or more) musical tracks, and lays them over one another so that they sound like they are fused into one song. This has become pretty common in the world of music, but Super Mario XP is the first video game mash-up I've played.
The game is fundamentally old-school Super Mario Bros., but with a layer of Castlevania added to it. In an introduction that is by itself worth the price of admission, Bowser does his usual bit of kidnapping the Princess, and now Mario heads through seven worlds to save her. You'll face the usual gamut of Koopas and Goombas and hit "?" blocks with your head to gain power-ups, but the gameplay has been infused with elements of Castlevania. Mario no longer shrinks to a smaller size when hit; he has a life bar, which allows him to take a few blows and is replenished by snacking on mushrooms. You can grab Fire Flowers and Hammers as sub-weapons, but Castlevania's perennial Cross boomerang also makes an appearance from time to time. Also, you must now collect Hearts in order to throw weapons, and Mario has a Dracula X-style "Item Crash" for each one that delivers multiple blows at the expense of ten hearts.
While the gameplay, world and enemies are mostly Mario, the music is just about all classic Castlevania tunes, and it is amazing how well they work in a Mario platformer. The urgent baroque music combined with the perilous levels, furious attacks of the bosses, and the gruesomely bloody death (complete with anguished scream) in store for Mario when he fails all add up to a fascinatingly dark edge for a game that stars the cheerful plumber.
It would just be a gimmick-fest, however, if the levels were not so well-designed, and the controls were not so precise to the familiar Mario standard. Mario no longer has the little "hop" after bouncing off an enemy head, but other than that, the physics and responses of the game world are very faithful emulations of the original Super Mario Bros. game. The levels are all new, although some have areas that resemble classic areas of both Mario and Castlevania games.
The game is fairly challenging, but no worries - your progress is saved at the end of each level, you can go back and play any cleared level anytime you like, and beating the game unlocks the traditional Castlevania "boss rush" mode. This being a Mario game, you are also bound to find some Warp Pipes hidden away here and there ...
The game does not have native gamepad support, so a key-mapping program will be necessary. As usual, I recommend JoyToKey (http://www.electracode.com/4/joy2key/JoyToKey%20English%20Version.htm), which is freeware and which allows you to save profiles for different games and switch between them easily. Super Mario XP uses the arrow keys for movement, left CTRL for sub-weapons, left SHIFT for jumping and Z for the Item Crash.