One of my favorite (and saddest) easter eggs in a game is in Detroit Becoming Human. Years before the game was released, a technology demo video was released by quantum dreams, called Kara. In Kara, the android (named Kara) is being assembled and going though a QA process. Part of that process has her speaking other languages and she sings in Japanese. During the QA, the technitian realizes that she is sentient and begins to destroy her. She pleads with him to spare her and he has a change of heart and lets her live. The video ends with her being put with the other non-sentient androids ready to be shipped out to stores.

Fast forward years later with the release of Detrit Becoming Human. One of the protagonasts named Markus is destroyed and sent to the junkyard. It is a truly awful place. There are hundreds of junked androids amongst the garbage and Markus has to salvage parts from other androids to repair himself. As he progresses in the level a faint singing can be heard. If the player follows the sound, they will encounter the remains of an old, junked android singing the same Japanese song. Is it THE Kara from the past or one of the same product line?

The Space Quest games are full of easter-eggs and references, but one that stands out to me is that in Space Quest I (the SCI version) when you take off from Ulence flats, a time pod arrives just as you leave.

Turns out that time pod contains you from the future, arriving from the events of Space Quest IV, so you have no idea that is actually a reference until you progress forward a few sequels and steal that very time pod in Space Quest IV to travel back to Space Quest I. As a bonus, when roger wilco returns to Space Quest I it is depicted as the AGI version of Space Quest 1 not the SCI version, so you never see the easter-egg from the opposite viewpoint but are instead given an easter egg to the earlier version of Space Quest I with roger sticking out like a sore-thumb in his 256 color glory against the 16-color backdrop.)

The literal Easter Egg in Grand Theft Auto: Vice City

Mine is kinda both an easter egg and a secret from Outer Wilds.

In a lab with core for black and white holes, you can actually break the fabric of space time by throwing your probe towards the black hole created by the first core. It will come out of the white hole before completely entering the black hole, so if you're quick enough and remove the black hole core, it disappears and there are now two probes, which will then destroy the fabric of space time. This gives you a game over. The easter egg part? You get an achievement called 'You've met with a terrible fate', a nod to Majora's Mask. The end credits also become really weird with a kazoo playing.

The whole thing is generally so damn nuts and cool, especially since the black holes in Outer Wilds managed to make me pretty scared to the point of dread when I fell in to one, which rarely happens in games. So it was kinda cool how it then also managed to make me laugh by just breaking the universe with a probe.

My favorite easter egg was the one in the Trials saga, which was incredibly hidden and, after exhaustive research, led to 4 people finding 4 keys buried in real locations, and a message saying that one of these keys will bi the one that opens the final box, under the Eiffel Tower, the 1st saturday of August in 2113.

My favorite secret might be the birthday cake in Castlevania: Portrait of Ruin. It's a health item you can only buy from the game's shopkeeper, Vincent, on your birthday.

I have a soft spot for this one because this was my first Castlevania game and one of the first DS games I remember playing. It's just a fun use of the new (at the time) internal clock and calendar mechanic.

Years ago, upon this forum I would meet and become friends with the man that would develop Dusk.

A while later I would meet and become friends with one of his brothers - who would go on to develop a very silly game: Rubber Duck and the Rainbow Gun (its available out there).

The pair of them have a pretty derpy sense of humour - which gave rise to a long running in joke of "When is the derpy brother update happening to your game?!".

Years pass and he comes back to the game to update a few things, add some QoL etc.

The joke returns - BUT - this time I had a derpy pixellated portrait of his brothers big derpy head.

AND LO IT DID HAPPEN!

It was added as a secret level and is now available for all to play - and for the few that find it they will have NO idea of what is going on unless they followed things, know us or read this post.

There IS a video of it out there, but as its been about three years I'm having difficulty finding it.

My favorite Easter Egg is The Federation Crash Site space shuttle with hypo sprays if fall out 2.

My favorite is in Rayman 3 where you could find the enemies from the last game (Rayman 2, the first game I remember playing) sitting at a table, in a secret room, posing as Jesus and his apostles in the last supper.
It feels like Easter eggs now a days aren’t made like that any more.

Oh well, at least we can still play and experience these Easter eggs in these good old games here on GOG! ;)

Probably from one of my favorite franchise, Gabriel Knight, in the very first game you can pick up books in the store and they will tease at the theme of the following games!

The Konami Code: Up, Up, Down, Down, Left, Right, Left, Right, B, A, Start.

In Conquests of Camelot, you need to visit the treasury before leaving Camelot.

If you enter 'ham and jam and spam a lot', you'll be greeted to a wonderful Monty Python and the Holy Grail easter egg, ending with a "In memory of Graham Chapman" message.

https://www.youtube.com/watch?v=VAkN4ZC9Q_E

It applies to many games - finding a cave behind a waterfall.

The dog ending for Silent Hill 2!

The Assassin's Creed Easter egg in The Witcher 2 finding the assassin that didn't survive the leap of faith.