I was wondering if there were any game creators designed specifically for making dungeon crawling hack n slash games such as like Diablo, Titan's Quest, etc. I would also prefer this program to be made for nonprogrammers who just want a simple program that can easily create levels with simple mouse clicks, drag and drops, or even lets you create your own objects with ms paint. But truthfully in the end, I just would like to know if anyone knows the most simple hack n slash game maker. Thanks :-)

Torchlight allows mods such as new characters, classes, quests, level editing etc. Scheduled to be released this month, you may want to take a look at that :)

This genre is pretty lacking in user-friendly game editors. The MMORPG engine genre is filling up fast, but Action-RPG has not experienced the same growth. As cNoob said, your best bet is going to be to learn to mod games, and start with mod-friendly commercial games like Neverwinter Nights 1 or 2, and others. Modding typically requires some kind of scripting, though, which is like watered-down programming. It is just hard to set up quests, story, etc., without doing some form of coding.

You need to balance originality with simplicity. For example, Titan's Quest comes with an editor for making maps, and I believe it can also be modded; or, as cNoob pointed out, the upcoming Torchlight allows the same. These would be relatively easy, but you ain't gonna be able design your very own battle system, gameplay, etc. And those mods will forever be tied to one specific game.

Moving up the latter of complexity, you can try something like Game Maker. I believe something like Diablo theoretically could be done with it, but it would take some work, and a good deal of scripting.

The next step would probably be a programming language (such as python), using a high-level library of some sort.

I don't know of any "game creators" specifically made for action RPGs, but you could peruse this list: Game Creation Resources.

I'm currently working on an action/rpg game creator which I hop to have finished by the end of the year. If you want to pm me you could tell me some of the features you're after and I can tell you if they will included or not.