Hi and a late welcome to PGD!

I'm curious about your project, just a few pieces of information and it sounds interesting already. Maybe you can post about it in the 'My Projects' forum?

However getting back on topic, I'd like to note that while you *can* use SDL alone to do alpha fading, it will not be all that fast. If your map 'screen' will contain a single image or sprite then depending on the hardware it should be ok. However try to do several alpha blended sprites or images on the screen at a time and you'll quickly see that it slows down significantly. If your end goal is to make heavy usage of the alpha blend then you may be moving into OpenGL territory. Just a little caution on the alpha blending usage with SDL graphics.