Gens is an emulator for ROM images designed for the Mega Drive/Genesis and 32X. The first version of Gens released was 0.01a on October 20, 1999, which was only capable of debugging instructions for the 68000. The first version released that actually played games was 0.1a, available as of December 18, 1999. Both of these initial versions were for MS-DOS only. The first version that ran on Microsoft Windows (initially called Wgens) was a beta of version 0.12, released on February 3, 2000.