- You gain more CpS the longer you've played in the current session.
"Actually not centuries-old. This one isn't a day over 86!"
It increases your CpS by a varying amount, depending on how long you have played without resetting. Like other eggs, this multiplier is "global", and is applied after the other multipliers (but it does stack additively with the other eggs).
The longer the session, the higher the multiplier, but with diminishing returns. It takes about 100 days for Century Egg to reach its maximum output of +10% (which allows a total of +22% gain from eggs). The formula is:
- where , and "days" is the current session's length.
Note: "days" can be fractional, up to 10 seconds of precision.
Note: This increase is added to the Easter global multiplier.
Note: The bonus is not locked in when you buy the upgrade. It will continually adjust to the appropriate value based on the length of the current session.
So this gives us the table:
|Session started||Global CPS|
While the item as a whole is a reference to the Chinese foodstuff hundred-year-old eggs, the second sentence of the description is a near-direct quote from the Discworld novel Interesting Times, in which Disembowel-Meself-Honourably Dibhala, cart-pushing purveyor of what is ostensibly food, is accused of selling substandard hundred-year-old eggs to the good burghers of Bhangbhangduc.