Comment by NikkiA

Sentinel (https://www.mobygames.com/game/16639/the-sentry/)

Mercenary (https://www.mobygames.com/game/10982/mercenary/)

and

Conqueror (https://www.mobygames.com/game/16593/conqueror/)

Sentinel is fairly well known, but by no means is it universally praised as some of it's contemporaries were.