According to gamelist.txt, it says that sometimes at the end of levels 7, 15, 23, and 31 (boss plane encounters), the boss never shows up and you get stuck forever waiting for it. This hasn't happened to me at all however. And for the record, I haven't found any differences between the regular and alternate sets of Zoo Keeper.(posted 10000 days ago)BTW Krool, great job on the 1942 score! I'm going to watch that recording now to figure out how you beat my score by 300,000+ points.