White is straining for the eyes. Even just reducing the blue light, making it more yellow, makes it easier for the eyes.
This is especially bad later in the day, as blue light can negatively affect sleep.
Also, I feel a parchment-like color is much more fitting a fantasy game than white is. White is too sterile, in my opinion.
Alternatively, you can also provide a dark theme. There's more background than text, so just inverting the colors is enough to drastically reduce eyestrain.