Easter season

Easter is a seasonal event in Cookie Clicker. It was added on May 18, 2014, with the 1.0464 update.

Since the 1.0466 update, Easter starts automatically and lasts from 7 days before Easter (Palm Sunday) to Easter itself (Resurrection Sunday).

File:BunnyBiscuit.png

Bunny biscuit

Easter can also be activated by purchasing the Upgrade "Bunny biscuit", which will launch it for 24 hours.

The Bunny Biscuit Upgrade becomes available after unlocking the "Season switcher",

The upgrade is repeatable, but it gets more expensive each time it is bought. When activated, It cancels any other seasonal event.

This season is one of two seasons to have its own Grandma form, the Bunny Grandma.

The golden cookies appearance during the Easter season:

Upgrades

Here is a list of the 20 Upgrades that are from the Easter Season. All upgrades are egg/larvae based in theme and can be unlocked randomly when clicking a Golden Cookie, Wrath Cookie, or popping a wrinkler. The price of purchasing each egg goes up based on the number of eggs purchased so far (${PE}$ in the chart below).

Icon	Name	Unlocked at	Price (cookies)	Description	ID #
File:Easter chicken egg.png	Chicken egg	"Common" eggs (see below).	$999*2^{PE}$	Cookie production global multiplier +1%. Cost scales with how many eggs you own. "The egg. The egg came first. Get over it."	210
File:Easter duck egg.png	Duck egg			Cookie production global multiplier +1%. Cost scales with how many eggs you own. "Then he waddled away."	211
File:Easter turkey egg.png	Turkey egg			Cookie production global multiplier +1%. Cost scales with how many eggs you own. "These hatch into strange, hand-shaped creatures."	212
File:Easter quail egg.png	Quail egg			Cookie production global multiplier +1%. Cost scales with how many eggs you own. "These eggs are positively tiny. I mean look at them. How does this happen? Whose idea was that?"	213
File:Easter robin egg.png	Robin egg			Cookie production global multiplier +1%. Cost scales with how many eggs you own. "Holy azure-hued shelled embryos!"	214
File:Easter ostrich egg.png	Ostrich egg			Cookie production global multiplier +1%. Cost scales with how many eggs you own. "One of the largest eggs in the world. More like ostrouch, am I right? Guys?"	215
	Cassowary egg			Cookie production global multiplier +1%. Cost scales with how many eggs you own. "The cassowary is taller than you, possesses murderous claws and can easily outrun you. You'd do well to be casso-wary of them."	216
File:Easter salmon roe.png	Salmon roe			Cookie production global multiplier +1%. Cost scales with how many eggs you own. "Do the impossible, see the invisible. Roe roe, fight the power?"	217
	Frogspawn			Cookie production global multiplier +1%. Cost scales with how many eggs you own. "I was going to make a pun about how these "toadally look like eyeballs", but froget it."	218
File:Easter shark egg.png	Shark egg			Cookie production global multiplier +1%. Cost scales with how many eggs you own. "HELLO IS THIS FOOD? LET ME TELL YOU ABOUT FOOD. WHY DO I KEEP EATING MY FRIENDS"	219
	Turtle egg			Cookie production global multiplier +1%. Cost scales with how many eggs you own. "Turtles, right? Hatch from shells. Grow into shells. What's up with that? Now for my skit about airplane food."	220
	Ant larva			Cookie production global multiplier +1%. Cost scales with how many eggs you own. "These are a delicacy in some countries, I swear. You will let these invade your digestive tract, and you will derive great pleasure from it. And all will be well"	221
File:Egg3.png	Golden goose egg	"Rare" eggs (see below).	$999*3^{PE}$	Golden cookies appear 5% more often. Cost scales with how many eggs you own. "The sole vestige of a tragic tale involving misguided investments."	222
File:Easter faberge egg.png	Faberge egg			All buildings and upgrades are 1% cheaper. Cost scales with how many eggs you own. "This outrageous egg is definitely fab."	223
File:Egg6.png	Wrinklerspawn			Wrinklers explode into 5% more cookies. Cost scales with how many eggs you own. "Look at this little guy! It's going to be a big boy someday! Yes it is!"	224
File:Egg5.png	Cookie egg			Clicking is 10% more powerful. Cost scales with how many eggs you own. "The shell appears to be chipped I wonder what's inside this one!"	225
File:Omelette egg.png	Omelette			Other eggs appear 10% more frequently. Cost scales with how many eggs you own. "Fromage not included."	226
File:Egg4.png	Chocolate egg			Contains a lot of cookies. Cost scales with how many eggs you own. "Laid by the elusive cocoa bird. There's a surprise inside!"	227
	Century egg			You gain more CpS the longer you've played in the current session. Cost scales with how many eggs you own. "Actually not centuries-old. This one isn't a day over 86!"	228
File:Egg.png	"egg"			+9 CpS. "hey, it's "egg""	229

Unlocking Eggs

Eggs are unlocked randomly during the easter season by either popping wrinklers or clicking Golden/Wrath Cookies. At base, a Golden/Wrath Cookie has a 10% chance to unlock an egg and a wrinkler has a 2% chance to unlock an egg. The "Santa's Bottomless Bag" and "Omelette" upgrades, as well as the Hide and Seek Champion achievement all increase the chance to unlock an egg.

There are many factors that can reduce the fail rate.

	factor
Wrinkler	0.98
Golden/Wrath Cookie	0.9
Hide & seek champion	0.7
Omelette	0.9
Starspawn	0.9
Selebrak, Spirit of Festivities	0.9/0.95/0.97 (Diamond/Ruby/Jade)
Santa's Bottomless Bag	0.9
Mind Over Matter	0.75

You can cheat a bit with eggs (and other rare wrinkler's drops). The thing is - if you pop a wrinkler and reload the page without saving - the wrinkler is back. So you can save the game, pop your wrinklers and if they drop nothing - reload the page. Repeat till they drop something.

Egg Spawn Probabilities

Fail rate to generate eggs
From Wrinkler	Santa's Bottomless Bag / Omelette Egg / Starspawn
	with none	with one	with two	with three
Base	98%	88.2%	79.38%	71.44%
With Hide and Seek Champion	68.6%	61.74%	55.57%	50.01%
With Mind Over Matter	73.5%	66.15%	59.54%	53.58%
With both	51.45%	46.31%	41.67%	37.51%

Fail rate to generate eggs
From Golden/Wrath Cookie	Santa's Bottomless Bag / Omelette Egg / Starspawn
	with none	with one	with two	with three
Base	90%	81%	72.9%	65.61%
With Hide and Seek Champion	63%	56.7%	51.03%	45.93%
With Mind Over Matter	67.5%	60.75%	54.68%	49.21%
With both	47.25%	42.53%	38.27%	34.45%

Egg Unlock Probabilities

When an egg is generated, there is a 10% chance for it to be a rare egg, otherwise it is a common egg.

If the generated egg has already been unlocked, then a second egg is generated. This reduces, but does not nullify, the effects of already having a number of eggs on your chances of finding new eggs. Having more eggs reduces the chance of you finding other eggs quadratically.

The probability of generating a new egg can be calculated using the following formulas:

• Pr(success)$=1-{\frac {9n^{2}}{1600}}-{\frac {3nr}{1600}}-{\frac {r^{2}}{6400}}$$=1 -0.005625 n^2-0.001875 n r-0.00015625 r^2$
• Pr(normal)$={\frac {9}{10}}-{\frac {3n}{400}}-{\frac {9n^{2}}{1600}}+{\frac {9r}{800}}-{\frac {3nr}{3200}}$$=0.9 -0.0075 n-0.005625 n^2+0.01125 r-0.0009375 n r$
• Pr(rare)$={\frac {1}{10}}+{\frac {3n}{400}}-{\frac {9r}{800}}-{\frac {3nr}{3200}}-{\frac {r^{2}}{6400}}$$=0.1 +0.0075 n-0.01125 r-0.0009375 n r-0.00015625 r^2$
• Pr(omelette)$={\frac {1}{80}}+{\frac {3n}{3200}}+{\frac {r}{6400}}$$=0.0125+0.0009375n+0.00015625r$

where n is the number of normal eggs already unlocked, and r is the number of rare eggs already unlocked. Pr(success) is the chance of unlocking a new egg, Pr(omelette) is the chance of unlocking the Omelette egg that will increase the spawn rate of eggs.

Probability of unlocking a new egg (when an egg is generated)

		Number of rare eggs already unlocked
		0	1	2	3	4	5	6	7	8
Number of normal eggs already unlocked	0	1.	0.999844	0.999375	0.998594	0.9975	0.996094	0.994375	0.992344	0.99
	1	0.994375	0.992344	0.99	0.987344	0.984375	0.981094	0.9775	0.973594	0.969375
	2	0.9775	0.973594	0.969375	0.964844	0.96	0.954844	0.949375	0.943594	0.9375
	3	0.949375	0.943594	0.9375	0.931094	0.924375	0.917344	0.91	0.902344	0.894375
	4	0.91	0.902344	0.894375	0.886094	0.8775	0.868594	0.859375	0.849844	0.84
	5	0.859375	0.849844	0.84	0.829844	0.819375	0.808594	0.7975	0.786094	0.774375
	6	0.7975	0.786094	0.774375	0.762344	0.75	0.737344	0.724375	0.711094	0.6975
	7	0.724375	0.711094	0.6975	0.683594	0.669375	0.654844	0.64	0.624844	0.609375
	8	0.64	0.624844	0.609375	0.593594	0.5775	0.561094	0.544375	0.527344	0.51
	9	0.544375	0.527344	0.51	0.492344	0.474375	0.456094	0.4375	0.418594	0.399375
	10	0.4375	0.418594	0.399375	0.379844	0.36	0.339844	0.319375	0.298594	0.2775
	11	0.319375	0.298594	0.2775	0.256094	0.234375	0.212344	0.19	0.167344	0.144375
	12	0.19	0.167344	0.144375	0.121094	0.0975	0.0735938	0.049375	0.0248438	N/A

Probability of unlocking a normal egg (when an egg is generated)

		Number of rare eggs already unlocked
		0	1	2	3	4	5	6	7	8
Number of normal eggs already unlocked	0	0.9	0.91125	0.9225	0.93375	0.945	0.95625	0.9675	0.97875	0.99
	1	0.886875	0.897187	0.9075	0.917812	0.928125	0.938437	0.94875	0.959062	0.969375
	2	0.8625	0.871875	0.88125	0.890625	0.9	0.909375	0.91875	0.928125	0.9375
	3	0.826875	0.835313	0.84375	0.852188	0.860625	0.869063	0.8775	0.885938	0.894375
	4	0.78	0.7875	0.795	0.8025	0.81	0.8175	0.825	0.8325	0.84
	5	0.721875	0.728438	0.735	0.741563	0.748125	0.754688	0.76125	0.767813	0.774375
	6	0.6525	0.658125	0.66375	0.669375	0.675	0.680625	0.68625	0.691875	0.6975
	7	0.571875	0.576563	0.58125	0.585938	0.590625	0.595313	0.6	0.604688	0.609375
	8	0.48	0.48375	0.4875	0.49125	0.495	0.49875	0.5025	0.50625	0.51
	9	0.376875	0.379688	0.3825	0.385313	0.388125	0.390938	0.39375	0.396563	0.399375
	10	0.2625	0.264375	0.26625	0.268125	0.27	0.271875	0.27375	0.275625	0.2775
	11	0.136875	0.137812	0.13875	0.139688	0.140625	0.141562	0.1425	0.143438	0.144375

Probability of unlocking a rare egg (when an egg is generated)

		Number of rare eggs already unlocked
		0	1	2	3	4	5	6	7
Number of normal eggs already unlocked	0	0.1	0.0885938	0.076875	0.0648438	0.0525	0.0398438	0.026875	0.0135938
	1	0.1075	0.0951563	0.0825	0.0695313	0.05625	0.0426563	0.02875	0.0145313
	2	0.115	0.101719	0.088125	0.0742188	0.06	0.0454688	0.030625	0.0154688
	3	0.1225	0.108281	0.09375	0.0789063	0.06375	0.0482813	0.0325	0.0164063
	4	0.13	0.114844	0.099375	0.0835938	0.0675	0.0510938	0.034375	0.0173438
	5	0.1375	0.121406	0.105	0.0882813	0.07125	0.0539063	0.03625	0.0182813
	6	0.145	0.127969	0.110625	0.0929688	0.075	0.0567188	0.038125	0.0192188
	7	0.1525	0.134531	0.11625	0.0976563	0.07875	0.0595313	0.04	0.0201563
	8	0.16	0.141094	0.121875	0.102344	0.0825	0.0623438	0.041875	0.0210938
	9	0.1675	0.147656	0.1275	0.107031	0.08625	0.0651563	0.04375	0.0220313
	10	0.175	0.154219	0.133125	0.111719	0.09	0.0679688	0.045625	0.0229688
	11	0.1825	0.160781	0.13875	0.116406	0.09375	0.0707813	0.0475	0.0239063
	12	0.19	0.167344	0.144375	0.121094	0.0975	0.0735938	0.049375	0.0248438

Probability of unlocking the omelette egg (when an egg is generated)

		Number of rare eggs already unlocked
		0	1	2	3	4	5	6	7
Number of normal eggs already unlocked	0	0.0125	0.0126563	0.0128125	0.0129688	0.013125	0.0132813	0.0134375	0.0135938
	1	0.0134375	0.0135938	0.01375	0.0139063	0.0140625	0.0142188	0.014375	0.0145313
	2	0.014375	0.0145313	0.0146875	0.0148438	0.015	0.0151563	0.0153125	0.0154688
	3	0.0153125	0.0154688	0.015625	0.0157813	0.0159375	0.0160938	0.01625	0.0164063
	4	0.01625	0.0164063	0.0165625	0.0167188	0.016875	0.0170313	0.0171875	0.0173438
	5	0.0171875	0.0173438	0.0175	0.0176563	0.0178125	0.0179688	0.018125	0.0182813
	6	0.018125	0.0182813	0.0184375	0.0185938	0.01875	0.0189063	0.0190625	0.0192188
	7	0.0190625	0.0192188	0.019375	0.0195313	0.0196875	0.0198438	0.02	0.0201563
	8	0.02	0.0201563	0.0203125	0.0204688	0.020625	0.0207813	0.0209375	0.0210938
	9	0.0209375	0.0210938	0.02125	0.0214063	0.0215625	0.0217188	0.021875	0.0220313
	10	0.021875	0.0220313	0.0221875	0.0223438	0.0225	0.0226563	0.0228125	0.0229688
	11	0.0228125	0.0229688	0.023125	0.0232813	0.0234375	0.0235938	0.02375	0.0239063
	12	0.02375	0.0239063	0.0240625	0.0242188	0.024375	0.0245313	0.0246875	0.0248438

Average Unlock Time

If we unlock easter eggs using only Golden Cookies, the average number of Golden Cookie clicks required to unlock all easter eggs can be calculated. The calculation includes the effects of unlocking the Omelette egg (whenever it spawns naturally). Therefore, please ignore omelette factor when calculate the fail rate in this section.

The result curve is very similar to Log-normal distribution. For each fail rate we may fit the probability curve to Log-normal distribution to find the parameter μ and σ. Then we can use the formulae on Wikipedia to obtain the probability we want.

For example, at fail rate 0.9, if you clicked or popped 753 objects, then there is 50% change to collect all easter eggs.

Number of object needed to unlock all Easter Eggs

fail rate	50%	75%	95%	98%	Log-normal distribution
					μ	σ
0.98	2351	3524	6310	8066	7.7625	0.6003
0.97	1755	2515	4218	5245	7.4704	0.5330
0.96	1437	2005	3241	3967	7.2700	0.4946
0.95	1231	1691	2670	3236	7.1157	0.4706
0.94	1085	1474	2291	2759	6.9890	0.4546
0.93	973	1313	2019	2420	6.8808	0.4435
0.92	885	1188	1812	2166	6.7858	0.4356
0.91	813	1087	1649	1966	6.7009	0.4298
0.9	753	1003	1516	1804	6.6240	0.4254
0.875	637	845	1269	1506	6.4575	0.4185
0.85	554	733	1096	1299	6.3176	0.4148
0.825	491	649	968	1146	6.1965	0.4128
0.8	441	582	868	1027	6.0895	0.4116
0.75	367	485	722	854	5.9062	0.4108
0.7	315	416	619	732	5.7526	0.4106
0.6	246	324	483	571	5.5034	0.4110
0.5	201	266	396	469	5.3050	0.4113
0.3	148	196	291	345	4.9982	0.4112

Cookie Production Global Multiplier

The cookie production global multiplier that many of the eggs modify is essentially another form of cookie multiplier, but it applies separately in the process(usually to smaller effect than +1% cookie multiplier would).

The final CpS formula is essentially: CpS * Cookie Multiplier (cookie types, Heavenly Chips, frenzy/elder frenzy bonus/clot penalties, etc.) * Global Multiplier

For example, if you have some cookie types and kitten bonuses totaling a 1000% cookie multiplier, and a base CpS of 10,000, giving you a total income of 100,000 cookies per second, and you unlocked two common eggs, your new total CpS would be 102,000 (10,000 * 10 * 1.02). If you then unlocked another kitten upgrade increasing your base cookie multiplier to 1500%, your income would increase to 153,000 (10,000 * 15 * 1.02)

Achievements

List of known Achievements that will be earned eventually from the Easter season.

Icon	Name	Description	ID #
Hunt is on - achievement	The hunt is on	Unlock 1 egg.	166
File:Easter quail egg.png	Egging on	Unlock 7 Eggs.	167
File:Egg2.png	Mass Easteria	Unlock 14 Eggs.	168
File:Egg3.png	Hide and seek champion	Unlock all the eggs. (20)	169

Note: The eggs only need to be 'found' for the achievements to be earned, they do not need to be purchased. While this may not matter since most eggs will end up being purchased, it is handy to know that situationally functional eggs like the Chocolate Egg, Century Egg and "egg" do not have to be purchased for the achievement.

Trivia

• The description of the upgrade "Duck Egg" is a reference to a popular YouTube video, "The Duck Song."
• The omelette's flavor text is a reference to the "omelette du fromage" episode of Dexter's Laboratory.
• The salmon roe flavor text is a reference to a song in the anime Tengen Toppa Gurren Lagann.
• The Century egg is an ingredient in Chinese cuisine .
• The Shark egg's description is from the thoughts of sharks in one of Orteil's other games, Nested. It is possibly also a reference to the sharks from the Pixar film "Finding Nemo".

• The Bunny Grandma bears a striking resemblance to Frank, a character from the 2001 film 'Donnie Darko'.
• The robin egg's flavor text is a reference to the catchphrase of Robin from the 1960s Batman TV Series.
• The Golden Goose Egg's flavor text is a reference to Jack and the Bean Stalk, as well as a related idiom: "killing the goose that laid the golden eggs ."
• The Bunny biscuit text is a reference to one of the rabbit myths told in Watership Down.
• The "egg" bears a strong resemblance to Yoshi's eggs from Super Mario World and a normal Pokémon egg from the game series "Pokémon". This pattern is also similar to a default spawn egg from Minecraft .
• Orteil said that the flavor text for "egg" is neither a pun nor a reference. However, in French, "an egg" is pronounced "un œuf" which sounds exactly like "neuf" = 9.
• Mass Easteria is a reference to the French band Mass Hysteria.