Keep in mind this topic isn't specific just to games made in Game Maker. Name some more things and I'll add them to the list.

-I especially like games where there's a "deeper" relationship with NPCs, like in Majora's Mask. And dating sims.

-A way to dodge unecessary random battles, if applicable, is good when needed, like repels in Pokemon.

-Useful rewards for various quests, side- and main- wise.

-Post-game content in which you can use that powerful weapon you probably got after beating the final boss is nice. Even just a good ending that closes all the plot branches is fine. "A Winner is You" doesn't fly with me.

But those go for games in general, RPGs specifically.

I updated the original post. I changed/condensed some of them slightly, but I did give credit - something I actually believe in giving people who contribute things.

Why are we making this list? I'd like to know before I contribute.

I wanted to put together a list of general ideas that are often overlooked, similar to what Quicky did (though this time not strictly Mario-centric) many years ago. I was planning on posting this list at a few other places (especially MFGG) once it was more fleshed-out.

Don't people already know what makes a good game?

A lot of the people making games actually don't, and besides, I'm trying to list things most people haven't really thought of.

Alright then, most people haven't thought of an interesting story.

Very useful list. I like it a lot; I'll try to use this in my games.

Scanlines with a customizable pallete. Good for BGs. I've seen them in SMW hacks.