The Sims 4 (unresurfaced prototypes of simulator game; 2008-2014)
During the development of The Sims 4, various prototypes of the game existed. One of the prototypes is for an online game that was originally going to be the successor to The Sims Online, and another prototype is an interactive. However, these prototypes were scrapped and later restructured into the final game
Project Olympus (Multiplayer Prototype)
In 2008, when The Sims 3 was still in development and The Sims Online closed, EA started to develop a successor to The Sims Online called Olympus (also known as The Sims Olympus, Project Olympus and The Sims 4). The game was in development for four years until it was scrapped in 2012. The Sims 4 was originally going to be a multiplayer-based life simulation video game, similar to The Sims Online. Originally, the logo of The Sims 4 replaced the iconic green plumbob with a blue plumbob.
The game uses a similar engine to The Sims 3, though the engine and its interface were tweaked for multiplayer. Originally, various multiplayer features that were used in The Sims Online were to return in Olympus. Features that were suggested in the Olympus prototypes includes player chat, group chat, and others.
On April 25, 2013, several screenshots from mock-up flash videos of the user interface were leaked online.
Chi Chan's Prototype
In early 2015, Chi Chan (the Studio Art Director for Maxis) posted some of the concepts and designs during The Sims 4's development. Unlike the Olympus prototype, it is an interactive prototype. However, EA took it down later. The only surviving bits from the Chi Chan prototype are screenshots, videos, and information about it.
Unlike all Sims games, this is the only the prototype build of the game to be developed in the Unity engine.