globally a good game, but many things to work on.
graphics:
-there are two skins for levels, the green ones and the red ones. Red ones are ok but for green ones it is sometimes hard to make the difference between background landscape and physical objects. You should make the non-physical objects less bright. On one level it was merely hard to find all nuts.
-Dogs are dreadful, but I guess you already knew.
-the indication of number of acorns in the top left corner is not readable on light blue sky. You should put a background board or use a different font for this indication.
Gameplay:
-moving platforms have two problems : First you do not move with then when you step on it. Next it is hard to prevent the end of run of the platform. You could display the path with some kind of rail, or you could make the platform slow down then accelerate when changing direction.
-jumping on mushrooms is a little hazardous. You sometimes make big bounds, sometimes small ones.
-cycles are long. You sometimes have to wait quite a while for a platform to come back or for a dog to go away. It's boring.
-on levels where there are platforms near to top border, you bump into the top border.This shouldn't be.
-Some levels are too difficult. You should let people reach the next level with one or two acorn missing and put a medal system to reward players who get every acorn.
-what's the point of flame throwers ? they just vanished each time I came near them. Are they enemies ?
Control:
-As you often have to start again a level, you should put a shortcut for that (I suggest R key)
-When you finish a level or when you die, it would be nice to put the jump key as shortcut for "next level" or "try again". As you don't need the mouse to play, it is a pain to use it in menus.