Three developers built the engine because the commercial alternatives didn't fit their specific project — too heavy, too expensive to license, or too opinionated about how a game should be structured. They never intended to release it.
A rough public version, shared mostly so other developers could report bugs, quietly attracted a small following. Within two years, studios far larger than the original team were shipping commercial titles built on it.
An engine nobody meant to publish
The team still maintains it part-time, alongside their own projects, largely unpaid beyond modest donations from studios using it commercially. None of the three expected the engine to outlast the game it was originally built for.
They've turned down two acquisition offers from larger companies, wary that a corporate owner would prioritize enterprise features over the lightweight simplicity that made it useful to small teams in the first place.