Plants vs. Zombies Garden Warfare 2 is a game developed by PopCap and published by EA. It is a game with many secrets. This guide will show you some of the secrets that you can find in the hub world, including the pipe, and the target range room.
The first secret you can find is located in the sewers. First, you have to head into the sewer through the entrance in Zompark as a Scientist, Citron Ball, or Super Brainz. Next, get on the railing above the pipe marked in this image. Going down this pipe will get you as close as you can be to the entrance of the secret pipe room.
Next, go to the end of the pipe so you're under the ledge you were on before. You should see a hole in the wall in front of you. That's the entrance to the room.
Finally, prepare to enter the hole using an ability depending on the character you are: Warp into it if you're Scientist, Ball Dash if you're Citron, or Heroic Kick if you're Super Brainz. Inside the hole, you will find 100,000 coins and 2 backyard customizations, one for each side. Cheers!
To enter the secret target range room, you'll need to have unlocked the large wooden door in the sewers for 5 stars, which allows you to access the target range. You don't have to be any particular character to get in this room, but the Peashooter, Super Brainz and Foot Soldier can get in the easiest. Start a game of target range (it's free) and continue until you reach this room.
Once, you get to this room, walk inside it and go over to this ledge with a gnome on it. To access the secret, you will need to jump on and over the ledge. All characters can do this with some difficulty, but Peashooter, Super Brainz and Foot Soldier can scale it in one bound using their Hyper, jump, and Rocket Jump respectively.
Once you get over the ledge, turn to your right and you will see a boarded up room. Break the boards by shooting at them, and claim the chest loot inside. Once you claim the loot, either respawn or complete the range normally to exit. Good luck!
