Why buy?
The day New Grounds is used as a demo/shareware site is the day Satan gets in a snowball fight with Hitler.
This game had an interesting concept; I liked it and thought that it had one up on the "three of a color" games this is inspired by.
However, this game strongly lacks a challenge. If I wanted to lose I figure I would have to go away from my computer for a few minutes, because this is so blatantly idiot-proof that it would be impossible otherwise.
Using this to pimp your "full version" might sell a few copies of your game, but it probably would have sold more if you had actually included some challenging elements. Moreover, the game does not have much of a "hook"; that point where you realize how the game works and the inherent challenge, thus inspiring you to start kicking pixellated ass.
The game overall is... well, a game. I can call it a complete, functional game, but that does not necessarily make it a good one.
Anyone who puts down money for the full version of this game is probably an idiot; fortunately, that seems to be the type of player you are catering to, so I suppose that it is a win-win situation for you. You get money, and the player gets pretty colors.