Firstly, I had no idea how inept I was at creating graphics. My graphics (maps and sprites were created using a combination of Mappy and Gimp) are pretty poor, but not only that, it took me about 3 hours just to figure out Mappy and finish with the single map I have so far.
So, I've decided to do a text-only version first, this way I don't have to worry about graphics or the presentation of them, I get to stick with what I'm used to.
Secondly, I have had no real experience playing text-based PBBG's, so I wasn't sure how fun they could be, until I played Urban Dead. That game did have its flaws (for instance, the lack of a tutorial, I spent awhile trying to break a barricade and wasted about 15 action points before giving up on that endeavor), but it was pretty neat. It did give me a feeling of being immersed in a zombie infested city, and I didn't need pretty graphics to help me figure out what was going on.
Now if I can create a game that gives the same feeling, but with my feature-set, storyline, environment, and a good, easy-to-understand tutorial I'll be on my way to a decent PBBG. I'm excited!