his hand? I hope you meant his head. also you should only need 1 sensor for hitting blocks.
But anyway just to get this out of the way, You should probably have sensors something like these:

Here is what I generally use. That includes:
-top sensor
-bottom sensor
-left/right sensors
-body sensor
-slide/jump sensor(optional)
-slope sensor(optional)
-edge sensor(optional)
example, if you wanted to make him bounce off those music notes, just make it so if the bottom sensor hits the music note, subtract from the gravity/make him bounce up.
For gravity, you'd do something like:
Always
-->Set Position Y to Y( "Player" )+value( "Counter" )
Every 00, 02 secs
Bottom sensor overlapping backdrop(negate)
--> Add 1 to counter
This way all the gravity is controlled by a counter. So when the bottom sensor hits music note, set counter to -6 for example.
This post has been edited by kirbyhi5 on Aug 31 2008, 07:40 PM