As you named a game Stardew Valley was my first idea. But a lot of essential tech tools, apps and libraries, are mostly one man creation (fitting in https://xk

As you named a game Stardew Valley was my first idea. But a lot of essential tech tools, apps and libraries, are mostly one man creation (fitting in https://xkcd.com/2347/ https://xkcd.com/2347/). I think that calibre, keepassx (no longer maintained, but living as keepassxc) and curl are some examples.