I liked the concept a lot but ...
The concept of being able to customize our game is pretty good. More artists should use it ...
But I guess you already know that so I'll give you now the usefull comments ... first you really should try to make levels ... I mean stages you'll be moving on ... it would be hard and long but it worth the effort ... with true levels your game will merit a 5 from me ... but for now it's a 3.5 ... it's way to repetitive.
It was good but as I said ... you could improve it to make something REALLY good with it! :)