Download :
http://www.blendswap.com/blends/view/75690
How it works:
Go to a ladder component and hold the e-key to climb up, down or sideways.
Every ladder component has a property called "ladder" and the PlayerBox searches for this property with a near-sensor.
Every time you near to an object that contains the "ladder" property you get a gameinfo "E-Key" on the screen so you know that you can climb.
P-Key.................Starts the Game Engine
W-Key.................Move forwards
S-Key.................Move backwards
D-Key.................Move to the right
A-Key.................Move to the left
Hold Spacebar.........Player moves faster
Q-Key.................Jump
F-Key.................Changed the daytime forward
B-Key.................Changed the daytime backward
E-Key.................Climb