Useful hints:
 Here's a very low-benefit trick for Zoo Keeper: 
 start the game and immediately crash into an animal. 
 If you have never jumped before this silly action, 
 you won't lose a life: the game will simply advise 
 you that you need to jump over animals to avoid them 
 and round 1 will start again from its beginning. 
 
 This seems actually to depend on a time limit. You 
 can get away with proceeding clockwise around the 
 cage, waiting at the spot where the first mug appears, 
 then moving to the second mug's spot. Immediately after 
 you collect the second mug, run into an elephant. The 
 way this usually works is that you have to jump two 
 elephants on your way around, but the game still gives 
 you a free life. Best of all, you get to keep the points 
 you scored!
 
 An obscure trick: On the coconut boards, when you jump 
 onto the top ledge, you get some points. Jump off the 
 ledge then onto it again: you'll get twice as many points. 
 And again, for four times as many. The bonus keeps doubling 
 until 300K per land. The best board to try this on is the 
 board where the ledges are invisible. It's kind of hard to 
 jump on then off, but so few coconuts are thrown that you 
 have lots of room for error.