The Battle of Polytopia contains seven confirmed Easter Eggs. (Easter Eggs are intentional, while bugs are not.)
In single-player, tapping an unoccupied tile in your territory ten times will spawn a Nature Bunny. Nature Bunnies have the Crush skill, enabling them to destroy any building and units on tiles they move to. Just like any unit, Nature Bunnies can attack, kill, and be killed.
Nature Bunnies can enter your cities, but cannot capture them.
In addition, Nature Bunnies cannot be converted with Mind Benders.Nature Bunnies cannot be spawned in online Multiplayer.
Luxidoor Easter Egg
Even if you don’t own Luxidoor, it still has a 10% chance of appearing as an opponent in your (single-player) games. The official reason for this Easter Egg is that it is an “apology” for Luxidoor is more expensive than other tribes (that is to pay for all that silk and their luxurious lifestyle!).Note that you can force Luxidoor to spawn if you do not own them by playing a 1v1 game and disabling all the tribes you own (except the tribe you are playing).
SunriseHolding the starry night sky background for 15 seconds causes the sun to rise, like in the Old Hoodrick proverb. The background will change to a pinkish-yellow color similar to the color of the menus. Hold the background again for 15 seconds or relaunching the app reverts this change.
Floating/Sinking CityAlternate tapping between the tiles on the bottom left and the bottom right of a city causes the city to float or sink. Tapping on the bottom left first causes the city to rise into the sky while tapping on the bottom right first causes the city to sink into the ground. (This is only cosmetic and does not prevent your city from being captured.)
Training a unit from the city or ending your turn reverts this change.
Mixed Tribes Easter Egg
Those who reached the highest deed can merge together in harmony. -Hintus Eastarius
If you have two tribes with three stars each, then this Easter Egg allows you to combine them together by tapping and holding the icons for both tribes in the tribe selection screen. The tribe you tap first determines the first part of the name, the city style, and the unit style of the mixed tribe. The tribe you tap second determines the second part of the name, the terrain, and the techs (including the starting tech and any special techs/units for special tribes) of the mixed tribe. Basically, the mixed tribe is the second tribe with the aesthetics of the first tribe.
If you own the Elyrion tribe and have 3 stars with them, then one of the languages available in the settings will be the Elyrion language.