Varth - Operation Thunderstorm is an arcade game released in several different versions. The version number (920612 etc.) suggests multiple releases or revisions, perhaps with minor differences in code or gameplay.  While the specific developer remains unknown, it's likely a standard arcade game with typical arcade gameplay such as shoot'em-up style gameplay and high scores.

Varth - operation thunderstorm (920612 etc)

Vapor Trail - Hyper Offence Formation (World revision 3)