I hope it right with you. :) It is an enjoyable game. If I were you, I would have a version with alternative graphics ready. If you get taken down after all, you can instantly re-upload the game with alternative graphics. Especially if you embed this to your own website. (Which you should!)
Yeah, I don't know if another copyrighted set is a good replacement for when you get taken down. See, if you just replace it with another set and you get taken down again, you can be seen as a repeating offender and get a higher penalty. The back-up best be an original. Luckily there are so many sets of graphics available which you could use.