Hmmmm, not sure about the resolution. You could try setting to windowed mode and see if that lets you choose lower resolutions. Or just resize the images after...
Viewing post in The Telwynium: Book Three comments
I did, it's in windowed mode. I dislike follscreen anyway and always prefer windowed settings. And resizing won't work because 11764:640 is not a whole number and the screenshots don't have clean, "crisp" pixels. "Telwynium 2" theoretically has the same settings and yet it opens in 640x400, I don't remember how I made it work lke that...