There's Wolf RPG Editor, although I haven't seen many people in the English RPG Maker community use it. (It's very popular in Japan.) Depending on exactly what you mean by "pixelated horror", you could also try Bitsy.

Sorry, I haven't used GameMaker in years so I didn't realize it was no longer free. Godot and Unity are both capable of doing 2D games. You could also work from scratch if you want to be a programmer. You could use HTML5/Javascript, or you could use SFML + C#. If you use C#, then you'll also be learning a language which is used in Unity, so you'll expand your ability into making 3D games.

I'm just speaking from a programmer perspective though. If you just want to make games but you're not interested in coding, there's lots of "2D" game making toolkits out there.