Physics, Physics, Physics.
Let the player choose EXCACTLY where they want thier chip dropped, and then make it a physics, and not luck based game from there on out. I would look at the game Sushi Cat as a good reference to what YOU should have done with this game. Overall, though, you still did a pretty good job and the game had an authentic feel to it, and I LOVED that it actually used my newgrounds account name in game, that was cool. Achievments were nice, but really not related to skill in any way, so they're not really worth much. Beyond that, I would suggest adding a "sandbox mode" where you get unlimited chips that you can plink to your hearts content.