Super Mario Bros is a 3D version of the classic Mario game. It's very simple, and not much different from the original.
You move back and forth by using the left and right arrow keys, and jump by using the up arrow. You can also move the camera using the W, A, S, and D keys and zoom in and out with the R and F keys.
As with the original game, you jump on top of enemies to kill them. If you jump onto a turtle, it will hide in its shell, and you then may hit it from the side to make it slide in that direction. It can be stopped by jumping on top of it again.
Overall it's a nicely-built clone and has a neat concept which will keep you entertained for hours.