Thanks for the comments. You can use passwords from the original game if you find any levels too hard. I did test and beat each level, so no level is impossible. Some may require more thinking than others. As for replacing the Sylvester clones, I am not at that level of hacking yet. I'm capable of changing graphics, text, and palettes on my own and use level editors for level editing. I actually think of myself as more of a designer rather than a hacker. My next hack, which is a Crazy Castle hack with Mario in it. (Sylvesters are Koopa Troopas, Yosemite is a Goomba, Daffy is a Shy Guy, and Wile E. is a Buzzy Beetle. Currently, I'm testing the last few levels and editing the opening sequence and ending picture. Hopefully, it will be finished by the end of this week.