I'm making this in a HTML5/JS canvas. It was a challenge to force the 64x64 pixel thing even on a 4K screen. The browser wanted it to smooth my game. I use two canvas elements. One in 64x64 resolution, the other adapt to the screen, then, I make sure imageSmoothingEnabled = false and I draw the 64x64 canvas, as an image on the other canvas. And voilà ! Just make sure to use integer positions and sizes to avoid any semitransparent borders etc.