Second Life

Just do whatever you did on Adventure Mode before. Be warned, however, because Crazy Dave will choose 3 plants at the beginning of each level for you, slightly increasing the difficulty, and Dr. Zomboss will have more health when fought in level 5-10. There will also be more zombies to be killed (levels 1-6 and 2-1 have added the Conehead Zombie) and there are also one more flag to be encountered on each level. You can also have a chance to achieve some other achievements like Good Morning, Pool's Closed, etc. In addition, you must look for the Zombie Yeti, it is hiding in the dark in Level 4-10. And flags that indicate huge waves of Zombies increase one in every level (Except Level 5-10).

Trivia

 * This achievement shows a picture of Crazy Dave saying "two". He also shows it on his fingers.
 * The hand sign also represents victory.
 * You should have obtained Zombologist (or cryptozobologist) if you obtained this achievement.
 * This acheivement is about 50% harder than Home Lawn Security/Resolute Homeowner.