Neat piece of fan-art here!
You did a really good job capturing the art style of the game with your choice of colours.
Seems like a blend of the game play art mixed with the cutscene drawings.
The only real thing I can critique is the small line going through Gary's legs.
It might be a wall in the background but Its hard to tell. It could be a wall that is slowly fading into the background, but this is purely speculation...:P
(Not going to mention scanner quality as that is out of your control, I'm only observing what YOU did with the drawing)
Other than that, good work! :P