- For the strategy guide, see Puzzle Mode/Strategy guide.
Think Hard is an achievement available for the Nintendo DS version of Plants vs. Zombies. It requires the player to complete the entire Puzzle Mode, earning a trophy for each level of I, Zombie and Vasebreaker. It is equal to both the I, Win and Smashing! achievements on other versions. In total, the player must get 18 trophies, 9 for each type of puzzle.
For the most part, Think Hard is easy to unlock. The only hard levels in either mode are Ace of Vase, because there is a Gargantuar and All your brainz r belong to us. The small amount of Sunflowers and large amounts of Potato Mines, Chompers, Squash, Magnet-shrooms, Starfruits, Threepeaters, Tall-nuts, and Split Peas also contribute to the difficulty factor.