alpha version

Short definition from Wiktionary

Noun

1. 1
   An early version of a program or application, typically unstable, but useful to show what the product will do. Sometimes this stage is referred to as a preview version. Sometimes no more features are added after this release, but bug fixes continue. This release comes after a pre-alpha version and before a beta version. As opposed to a beta version an alpha version is usually not feature complete.