I dont think you should change the style. Where would we be if someone said we cant do painterly like bastion. it looks too similar. I see nothing wrong with the main characters and others being shadows. who cares if its been done before. Let me see your take on it.
I semi-agree with that. Just because Jet Grind Radio did cell-shading first, doesn't mean Legend of Zelda: Windwaker or Borderlands shouldn't be cell-shaded.
However, even someone that hasn't played any of those three games before, can instantly tell they are different games and unrelated to each other's gameplay. None of them look like clones of the other.
On the other hand, Limbo has been played by over 3 million people. This is the exact same audience that zylski's game is going to be marketed to. You don't want journalists to down-rate their reviews, and lost sales from customers, because they mistakenly think your game is a clone. It definitely looks like a clone because of one single very noticeable similarity (the main character) that can be fixed in about two days work.
Unless it's a deliberate parody or commentary - See Braid's castle and Yoshi - you don't want people about to buy your game to think, "Oh, this is a cheap knockoff clone product attempting to cash in on another game's success. I think I'll pass.".
At the very least, make the character solid blue or something. Or use his silhouette as a mask into another texture that is fixed in the background, as if his body is a window into another dimension - or something! Do anything except exactly what a really recent, really similar, really widely-known game has already done.
