Microvision – Alien Raiders and Cosmic Hunter (1981)

The Microvision was the first cartridge-based portable system and had a total of 11 games. Alien Raiders and Cosmic Hunter were the only releases it had in 1981 but the exact order is undocumented.

Although no emulators for the Microvision exist, there is a nifty simulator at: http://home.comcast.net/~eichler2/microvision/MicroSimProject.htm (not mobile-friendly).