Originally released in Europe as StarRay, the 1988 North American release of Revenge of Defender is a modern reinterpretation of the arcade classic Defender.  Revenge of Defender intensifies the horizontal shoot-’em-up formula with lush parallax scrolling, detailed environments, and a new arsenal of alien threats. Players pilot a nimble fighter across seven visually distinct planets, each one packed with hazards ranging from silicon worms to energy-draining plants and swarms of living crystals. This enhanced remake retains the core objective—protect colonists from relentless alien abduction—while pushing the audiovisual boundaries of home computer hardware. Power-ups, smooth scrolling, and increasingly complex waves of enemies add depth to the classic gameplay loop.

Between the name of the Epyx release and the font treatment, we can’t imagine that the company didn’t work something out with Williams Electronics (the original creators of Defender).  In any case though, Epyx was the North American publisher for this Hidden Treasures title (known as StarRay in Europe).  Unfortunately, we’re unable to find anything out about what happened to Hidden Treasures, so we can’t advise on the state of the IP and where it may reside.  If you are really committed to tracking this down, you may want to start with Logotron, the European publishers, and see if they have any additional information.