But in vertical mode, the game fills the whole screen, and looks more like the original game.
I take it that a TV would display the same way?
If not, then a TV may be the way I need to go.
Yeah, a tv would display the same way, but the size of a 27", which you can get pretty cheap, would allow the screen to look just as big as a 21" vertical.
Assuming this is a 4:3 ratio crt, at 21" it should have a viewing angle on the horizontal of 16.8". When in vertical mode rotated that is what you would see for galaga. On a 27" tv sitting normal, if you played Galaga the screen would have black on the side but still be 16.2" tall.
You would have a little bit taller screen using a 21" monitor that rotates, but I don't know if you could use a crt. You would have to degauss it every time you rotated it because of the change in the magnetic field. Also the weight would be a big issue in rotating a crt.
Using the 17" screen would only give you a vertical monitor 13.6" high. A tv would offer more screen to watch.
If you don't want to see the black sides on the monitor, look up smoked plexi or smoked glass on this forum. You will see that the image just floats in the glass.