Thanks to itch.io I can see that this game was made with gamemaker. I am trying to make a game in gamemaker with HD graphics such as the ones in your game. However, all the edges of the graphics in my game are rough and pixelated. I was wondering how you got your graphics nice and smooth. Any info you could provide would be great. Thanks!
Sorry for late response, hope you have solved your issue already! Are you using GameMaker sprite editor? That might be the reason for rough edges. I create my graphics with Inkscape (or you could use other editor) and there's nothing really special about them. You might need to toggle "Interpolate colors between pixels" in graphic options of the platform to see if that improves anything.