When I started the game, I was afraid that the size of the images would make the game impossible to download. So I had the bad idea to make the images very small.
I'm gradually redesigning these images, replacing them with larger ones using a layout technique so that the overall size of the game doesn't explode. It's a long work, it will take a lot of updates to get all the images resized.
The "final" images are in HD 1280x720.
I don't plan to make them in 4K quality, first because it would make the game too big, and second because some players play in windowed mode and the images have to fit them too.
The RPGmaker VXace engine is at 540x416 native.
The problem is that I have to scale the image down to fit in this native resolution and it is re-aggrandized for full screen. I know that it increases the pixelation effect but I don't have a solution to this problem.
I just know that I will choose a better engine for my next game...