Indeed, there are a lot of holes to fill in. The problem is that the IP of the existing code and assets (graphics/designs) might be contested in court, if your

Indeed, there are a lot of holes to fill in. The problem is that the IP of the existing code and assets (graphics/designs) might be contested in court, if your project is successful enough to make money and therefore makes you a desireable target. As a non-lawyer offering non-legal advice, I suggest you rebuild the project from scratch (using a different language if possible/feasible, as well as different graphics) so that there can be no question as to whether or not you used code or graphics for which you do not hold the correct license (in the case of code) or copyright (in the case of graphics).