Sorry to dig up an older topic but I had to add my two cents... 😀
I had a Tandy 1000 TX back in the day with a CM-5 RGB monitor. For those who have never gamed on an authentic RGB monitor with a Tandy--you're missing quite a lot. The difference is as noticeable as gaming in CGA on a EGA/VGA tube versus a composite monitor.
The difference is huge.
I managed to get another CM-5 monitor recently and I plopped Thexder back on a Tandy just to be sure my memory isn't fooling me. It isn't.
Thexder looks many times better than the picture above of Tandy graphics on an RGB monitor than you can see with your current tech monitor. I'd say it almost looks like a cross between TGA (Tandy) and VGA due to the way the CM-5's displayed the images. This not only holds true for Thexder, but for all games in Tandy graphics. Bard's Tale is the same thing, even Sentinel Worlds looks amazing on a Tandy RGB monitor.
You have to see it to believe it. Thexder in particular takes on a more "metallic" tone to the world. You really feel immersed in it and it looks like you're battling machines an electronics. I'd take a screenshot but that might not do it justice. I can try. The thing that makes the RGB monitors of the time (you have to have an old one) is that you can see the individual Red Green and Blue elements so an advanced form of "dithering" takes place, as well as the brightness levels are much brighter--and, the tube gives the images a sort of "bilinear filtering" to the images.
Try one of these monitors. You'll be amazed and finally experience Thexder how it should be played. To be fair, I've played it on a PC-88 and others above are correct, it is more like the EGA version (sans multiple lasers at one time, we don't get this on the PC) but--the Tandy version looks the best by far. The PC-88 version sounds the best (and the Apple IIgs).