Trojan is an arcade game with regional variations. The "US set 1" and "US set 2" labels suggest different versions released in the United States, possibly with altered artwork, gameplay tweaks, or language changes. More research would be needed to pinpoint the developer and publisher.  The gameplay would likely involve strategic combat or a scrolling shooter mechanic; however, differences between these sets would require further study.  The existence of multiple sets suggests that the game enjoyed sufficient popularity to warrant different releases.

Trojan (US set 1)

Trog (prototype, rev 4.00 7/27/90)