Get the earth platypus egg without skipping the minigame.
It's another chess minigame!!!
The solution to this minigame isn't very complicated once you figure out that the gofer only moves like the knight in a game of chess (an L shape, 2 movements forward then 1 to the side).
Use the rocks on the side to block of 2 of the potential opening he can use then put the trap on the other. Click on the rodent to make him move and he'll move to the trap and you've got the egg... and the achievement with it.