@ryo Do you know who this guy is? He's the creator of CaveStory. He made it all by himself starting in his late college years and finished it in five years while having a family and a full-time job in the process.
And he did it all from scratch. He wrote the entire game in C++ and DirectX.
@ryo It was the first major indie game. It was released back in 2004 as freeware. It's an action-platformer with adventure elements. Not the official site but has all the info here.
His story is summed up in this video.
@nerdman @beardalaxy @ryo RollerCoaster Tycoon is probably the only thing closest to it (made by one guy and entirely in assembly), but he relied on others for art and the game was published by a third-party.