Super Mario Bros. X is a nice Mario fan game that mixes primarily elements from Super Mario Bros. 3 and World into one fine package (but you can also find some stuff from Super Mario Bros. 1, 2 and the classic Mario Bros). On top of that you get also a great working 2 player co-op mode!
So you have two options: You can either play it with a friend or try to master it alone by playing both Mario and Luigi at the same time by yourself (like i did as you can see from the video).
Maybe change the controls to control the characters independantly or leave the default settings alone which means that you control both Mario and Luigi simultanously with the arrow keys…
Fun!
Also watch the Trailer from the developer of the game to see some more stuff in action.
Moreover I recommend to check out the other carefully selected Mario related Games on Pixel Prospector
THIS SUCKS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
The split-screen concept is very clever. I like how the split is determined by where each player is, relative to the other.