Challenge Mode is the hardest mode in the game. The player must fully understand the game in order to beat it.
Challenge Mode is for experts of the game. The goal for this mode is the same as Adventure Mode: collect three egg pieces to finish the level. However, there are some twists, which pretty much makes Challenge Mode challenging.
Every 4 seconds, each item that is already opened will increase its price by 1% of its original price. Example, a guppy costs $100. 1% of it is $1. So, it's price will keep increasing by $1. Same goes with other items. A $200 food quality upgrade will keep increasing its price by $2. A $300 food quantity upgrade will keep increasing its price by $3.
Once an egg piece is bought, all items will reset back to its original price, except for the egg piece itself. Example, if you bought an egg piece and its price is $7000, it will stay like that. After the cooldown of about 15 seconds, that $7000 will again constantly increase. The egg price will keep increasing, until it maxes out at $99999.
The longer you take to finish the level, the peskier those aliens are gonna be. The longer you play, the harder they get. They'll increase in difficulty and in number. Too many aliens can make finishing the level impossible. So speed is an important factor of Challenge Mode. Take too long, you might not make it.
Another thing, after five minutes, purchase options that are still closed will be automatically opened by the game.
For every time the player completes a challenge, they will be given shells, and for the first 8 times, a story for pets and aliens. After getting all tank-specific stories (and you must have unlocked Brinkley, Nostradamus, Stanley, Watler, the upgrade that lets you have four pets per level, and the upgrade that lets your take seven additional pets in the virtual tank), the next time any (it can be Tank 1, 2, 3, or 4) challenge mode tank is completed (i.e. the 9th time), the 33rd story will be unlocked.
|1||2000||1-5, 21, 25 and 26|
|2||5000||2-10, 22, 27 and 28|
|3||10000||11-15, 23, 29, 30|
|4||20000||16-20, 24, 31, 32|
- See also: Challenge Mode/Strategies
The prices of items increase by 1% every 4 seconds, and later in the level, the alien difficulty will increase. Money-making pets are recommended to finish the level faster. You may also bring alien-attacking pets to deal with the increase of aliens later in the level. Buying an egg piece resets the prices of all items except the egg piece itself, so it is better to buy the egg pieces one at a time. A good pet combination to finish any challenge tank faster is Amp, Angie, Presto, and Walter. Clicking on Amp shocks the guppies for diamonds while Angie revives them. Click on Walter to activate Amp and make fish drop coins. During alien attacks, change Presto to Gumbo or Gash.