Underground is a stage that takes place , well... Underground.
You and Crazy Dave got an invitation for a tour to go to the underground mining facility. But, the zombies got there before you and have infected the miners. Now, you have to do what you gotta do. Kill em'!
Sun Amount Falling:
What will happen to:
Still normal except there are no flying zombies and Digger Zombies are a lot more common.
Lobbed-shots will just hit the ceiling so they are now useless. Cob Cannons will explode too because of the ceiling. Plants that shoot upwards and makes projectiles fall will have the projectiles hitting the ceiling.
No sun will fall. Also, ground might fall off the ceiling and squash your plants so be careful and always use Umbrella Steel.
Sometimes, the ground will erode and sink into deeper parts of the earth killing some of your plants. Some sinkholes already appear before the level. Also, in level 7 - 10, there will be 2 rows of water underground.
More coming soon
Last Line Of Defence:
The last line of defence here is a large drill that drills all of the zombies in a lane.