Just want to share about making pixel art games using Game Maker: Studio for device (Mobile device, like Android). The idea is how to resize the game according to the screen by using exact 2-4 times scaling, so the pixel art still looks pixely. You might want to see this article. Here is the link that I'm used to learn (https://forum.yoyogames.com/index.php?threads/scaling-resolution-and-aspect-ratio-management-for-game-maker.7106/)
Cheers