W. Eric Martin
I introduced this game to my family this weekend and my 10 year old sister really liked it. She kept requesting to play over and over even after everyone else was finished. Not wanting to deny her I came up with a quick variant to make a 2-player game a little more interesting.
I like the two-player game as is. You know that every chip not in your stack will end up in the opponent's, so you fight harder for majorities in animals. If you're good at counting, you can track such things and play to the odds when drawing or deciding to swap with a monkey.
Cheeky Monkey is vastly different when played with two, four or six, but I think in all cases the game works great under the published rules. You just need to adjust your playing style to account for how many opponents you face.