I bought this supergrafx in the '90. It is an upgraded version of the PC Engine, released exclusively in Japan, primarily in response to the Super Famicom by Nintendo. My SuperGrafx is of course in like new conditions.
It has originally announced as the PC Engine 2, the machine was purported to be a true 16-bit system with improved graphics and audio capabilities over the original PC Engine. Expected to be released in 1990, the SuperGrafx was rushed to market, debuting several months earlier in late 1989 with only modest improvements over the original PC Engine.
This version comes already with rgb video conversion so i can connect the console to a TV with a normal scart plug.
I own two dedicate games for Super Grafx; Daikamura it's a action platform by Capcom where you have to defect lots of demoniac creatures and save your princess. The game is well programmed, hard to play with awesome graphic.
The other one is Battle-Ace, is a shooter in after-burner style.