Just a test of some slightly more advanced platformer movement code. Left/right arrow keys to move, up arrow to jump.
The key to smooth movement is not to use keys to change position directly. Instead, you should have them change a "velocity", and then each frame, the position should be changed by the velocity. This gives the character a feeling of accelerating from point to point, instead of just automatically sprinting full speed and then stopping on a dime. You can tweak the acceleration to make them speed up faster, change the maximum velocity for the top speed, increase / decrease friction to simulate slippery surfaces, and change gravity or jump strength to play with different jump arcs!