Easter Eggs

Pong
Make a game named "Pong" (case doesn't matter) while in the garage. While coding the graphics part, the animation on the wall.
 * Title : Treasure Hunter.
 * Description : Activate the hidden treasure in the garage.

Wing Commander

 * Title : Bluehair Reporting For Space Duty

Name a game "Wing Commander" or "wing commander", while in the second office (before PC upgrade !).
 * Description : Little known fact: Cats go all aggro in space.

Doom
Name a game "doom", "DOOM" or "Doom" while in the second office.
 * Title : Welcome to Mars.
 * Description : How did I get here? Why is there a chainsaw? Who cares!

Half-Life
Name a game "half life" or "half-life" (case insensitive) while in the third office (after PC upgrade, before tech park).
 * Title : Best ride to work ever.
 * Description : Workplace safety anyone?

Theme Hospital
Name a game "Theme Hospital" or "theme hospital" while in the third office.
 * Title : Welcome to your hospital.
 * Description : Patients are reminded not to die in the corridors.

Halo
Name a game "Halo" (case insensitive) while in the fourth office, after having unlocked the R&D lab.
 * Title: Welcome Chief.
 * Description: This world is round but different.

Star Citizen
Name a game "Star Citizen" (case sensitive) while in the fourth office, after having unlocked the R&D lab.
 * Title : The sky is not the limit.
 * Description : Welcome back Chris. We've missed you.

Okami
Name a game "Okami" (case insensitive), "Ōkami" or "大神" while in the fourth office, after having unlocked the R&D lab.
 * Title : Painting with nature.
 * Description : Pay homage to a specific Japanese video game.

Game Dev Tycoon
Name a Game Dev Simulation "Game Dev Tycoon".
 * Title : Inception.
 * Description : Develop the game within the game.

Greenheart Games
Name your company Greenheart Games
 * Title : Admirer
 * Description : Fun fact: We almost named our company Megaflop Productions!

Existing Company
Name your company after one of the names in this list: Activision, Adventure Soft, Atari, Atlus, Bannter, Bethesda, Big Huge Games, Bioware, Blizzard, Bullfrog, Capcom, CCP Games, CD Projekt RED, Codemasters, Crytek, Electronic Arts, Epic Games, Epyx, Game Freak, id Software, Jagex, LucasArts, Maxis, Microsoft, Mojang, Naughty Dog, Nintendo, Paradox Interactive, Phillips, Playstation, Rare Ware, Raven Software, Rockstar Games, Sega, Sierra, Square Enix, Ubisoft, Valve, Westwood Studios; or any one of many others. A more comprehensive (but probably still incomplete) list is on the Achievements page.
 * Title : Fan
 * Description : Pick an inspired company name.

Portal
After being asked by Dave Johnson to put red explosive barrels in one of your games, create an action game and select "Red Explosive Barrels" as a feature during game creation. Entire achievement is Portal 1 & 2 reference. Dave Johnson is supposed to be Cave Johnson, founder of Aperture Science, in which Portal 1 & 2 take place.
 * Title : Eat Cake
 * Description : Show them red barrels some action.