I compile my game, as usual. I optimize all sprites to be MAX 512x512.
Our good friend CocoonJS helps me out, and makes the 512x512 textures 1024x1024. Why? I have no freaking idea.
I set up Texture Reducer to cut to 512x512 and what do you know, still 1024x1024. Useless.
Next up, 256x256 Texture Reducer. Oh, cool, the textures have dropped in size. RAM isn't obese. Nice. I come close to the images with my eye to inspect them, and they are not 512. They are blurry. Not retina.
I am absolutely certain that most other solutions are at least 800% less confusing than this.
Like making a button that says "Quit" and then it just continues the game.
EDIT: Textures get an increase in size even when Texture Reducer is DISABLED