Instructions
Select "Adventure" from the "Plants Vs. Zombies" main menu. There are five stages each, with 10 levels in this mode.
Play through "Adventure" until you reach Level 1-5. Crazy Dave introduces himself and offers the first challenge level. From this point on, challenge levels are played as the fifth and tenth level in each stage.
Complete Level 3-2 to unlock the mini-games option in the main menu. This allows you to play any of Crazy Dave's mini-game challenges any time you wish.
Select "Mini-Games" on the "Plants vs. Zombies" main menu, followed by the mini-game challenge you want to play. New challenges are unlocked as you complete them in "Adventure" mode and mini-game challenges in the "Mini-Games" mode.