Anybody wanna help me make my RPG game, FPT (Fnaf Mythology)?

If I get it (Which I probably will) I'm gonna make a RPG Game based off of one of my Idol's AUs! (Look at my one of my discussion posts for details) It's not Fnaf, but has characters from it and is based in medieval times! It's kinda like Undertale, but a million times better! (In my opinion)

I really need this game to make my fan made Fnaf Mythology game (Look at one of my discussion posts for details) But, I really want Pixel paint to make sprites and Pixel art with. Which game should I get?