Unreal Software uses 4 digits to describe versions. The first version is 0.0.0.1, the second one is 0.0.0.2 and so on. The number of used digits tells you if it is an alpha, beta or "final" version.
- 0.0.0.1 - 0.0.9.9: Alpha Versions
- 0.1.0.0 - 0.9.9.9: Beta Versions
- 126.96.36.199 - 188.8.131.52: Final/Gold Versions
The initial stage of development. Very early versions with either many things missing or many/critical bugs.
Switch to beta takes places when most important features are implemented and when there are no known "critical" bugs anymore.
Advanced version where nearly everything is implemented and working. It's still possible that bigger changes happen in this phase. Major work in this phase is fixing smaller bugs and optimizing things.
Software is never 100% done or bug-free. This phase just tells you that the game/program generally works as it is supposed to. Games in this state can be improved and extended as well.