Recently, an unusual build of the original The Sims appeared online. It is assumed that this is the very demo version that was able to confirm the viability of the life simulator idea.
The author of the YouTube channel LUCPIX demonstrated the gameplay. He claims that the build in question was created after the 1998 demo.
The blogger also noted that this prototype of The Sims 1 (1999) is the first known "working" version of the game, where they completely abandoned script-based storylines, i.e., the players themselves "are responsible for the stories of their families — without any scripted tutorials or pre-written dialogues offering us to choose which Sim to kiss in order to win."
If this version is genuine, then the community has managed to find the first (or one of the first) "proofs of concept" of The Sims with the gameplay formula that players know today.