lol blacka_cheeze don't make it too hard for yourself.
You will not be making an MMO.
As a first game you probably only want like 6 areas, 38 will be way too many. You will probably want multiple areas using the same tile set (same graphics). As a general thing with horror games you start off with the empty and ominous area (ghost town would be good), then slowly work your way through increasingly ominous areas, finally finishing up in the hell on Earth place.
Here is an example for progression. It's just an idea remember.
Abandoned town -> empty research facility -> overgrown facility depths -> dark caverns of scary shit -> super secret scary underground temple -> bloody demon altar
The last area could be the pit of bodies, where zombies crawl out of the ground, and you have to kill the huge patchwork zombie abomination. Depends on what your story is.
Get a story done first. The story will help give you direction, and you can use it to help decide exactly what areas you want. After you start making the zones you will probably need to change the story a bit, that is normal.
Keep the story written down, as you change it write those changes down so you don't forget.
The monsters, weapons, stats, etc you put in last, but they will also require a lot of work. Make the zone, explore it, make sure people know where they are going. Then you can put monsters in and such.
Remember don't make this game big. As a first attempt it will suck balls. Just get it done, and if you think it's decent then maybe get some other people to play it, host it online or something (trust me the game will not be good lol).
Last tip is google search for rpg game makers. You should get all the art assets and a decent engine for what you want, for free.