• The Limbo Page is a hidden amount of data in the PC version of Plants vs. Zombies that contains twenty mini-games (excluding Ice Level, Intro, Upsell, Zen Garden, Tree of Wisdom) along with four variations on Survival: Endless that were going to be added to the game, but were eventually canceled.
• They also could be "hidden" for players to find out on their own and use a hacking program to access it. It is possible to access this page via third-party memory editing programs such as Cheat Engine and changing specific data values. All mini-games (with the notable exception of Ice Level) are completely playable.

• Open Plants vs Zombies (you need to have Mini-Games unlocked tho)
  
• Open Cheat Engine and search for the processes.
  
• Select "popcapgame1.exe"
  
  
• Click "Memory view."
  
  
• Right click on any of the lines, and select "Go to address"
  
  
• Search for address "00431CE0"
  
• Select "Replace with code that does nothing."
  
  
• Press "OK"
  
• Done! Enjoy those canceled mini-games!

• Art Challenge Wall-nut: Place Wall-nuts in the outlined spaces to create one giant Wall-nut.
  
• Sunny Day: Here, everything is normal, but all Sun from the sky is big, and they give 50 sun units, instead of the normal 25.
  
• Unsodded: Rows one and five cannot be planted on, but zombies still appear in those rows.
  
• Big Time: Here, Sunflowers, Marigolds, and Wall-nuts are all twice their normal size, increasing their original abilities.
  
• Art Challenge Sunflower: Place Starfruits, Umbrella Leaves and Wall-nuts in the outlined spaces to create a large Sunflower.
  
• Air Raid: A Fog level that has a very high amount of Balloon Zombies.
  
• Ice Level: A broken level supposed to be covered in ice and snow where the Zombie Yeti and some scrapped zombies would appear.
  
• High Gravity: On this Roof level, very high gravity causes projectiles to only hit the tile in front of it. Balloon Zombie's balloon pops after going a few tiles. Catapult plants hit at a slightly farther range.
  
• Grave Danger: Zombies only surface from graves during this mini-game, and more graves appear frequently.
  
• Can You Dig It?: The lawn is full of Wall-nuts and the only plant the player can plant are Peashooters.
  
• Dark Stormy Night: Basically like Level 4-10, but with different plants and zombies.
  
• Bungee Blitz: The same as Level 5-5 in Adventure Mode.
  
• Intro: The beginning sequence of the game, then puts the player into Adventure Mode instantly.
  
• Survival: Day through Roof Endless (Except Pool): The same as Survival: Endless, but inside the Day, Night, Fog, and Roof areas, respectively. There is no pool variant due to Survival Endless already taking place in the pool.
  
• Upsell: Crazy Dave convinces the player to upgrade to the full version of Plants vs. Zombies.
  
• Squirrel: The player is to find seven squirrels by digging up Wall-nuts, one of which has a Zombie in it. Does not appear in the Limbo Page.

• Squirrel is one of the 17 hidden mini-games that was canceled from the game.
• The goal of this game is to find seven squirrels before the Zombie reaches the player's house. The lawn is full of Wall-nuts. The Wall-nuts will flash for one second from being bitten. One of the Wall-nuts will contain a zombie and some squirrels. There are no peashooting plants, instant kills, or Sunflowers, so the player will have to find all the squirrels before the zombie reaches the player's house.

• Open PVZ and your Cheat Engine.
  
• Go to ZomBotany and key in 16 in the value bar (Or any other mini-game. Just know the ID of the minigame). Click First Scan.
  
• Then go to Seeing Stars and key in 22 in the value Bar. Click Next/New Scan.
  
• When the address appears, change it to 49.
  Notice: If you have more than one address in the result, repeat the steps until you get one result. Make sure to change the value before the seed selection dialogue appears.

Codes are words that can be entered during gameplay to affect the zombies (except for trickedout). They may be typed at any time while the game is running. The effect is applied after the last letter is typed; there is no need to press enter.

Information was taken from PVZwiki.
If you have any problems write me or in the comments section.