woot for a lit map.
I think the gameplay will be eerm, a bit boring with just one way, I would make more of them.
I haven't had time to download and try it but the walls and the ground and everything seems a bit boring, maybe try making some details?
And for example in the second screenshot the walls are misaligned, easy to fix with a small map like that.
When you change the name, make sure to put _b1 in the end of it. And use small letters only.
At least from the screenshots this looks your best map by now, congrats.