The invisible barriers are shown below.
This map could benefit from some improvements if anyone likes the idea and cares to edit it. I wanted to create a map that requires a different strategy, but not really sure yet how well it will play.
I don't care too much about credit, so if anyone edits the map, he is welcome to put his name to it.Download mgm file
<br /><span xmlns:dct="http://purl.org/dc/terms/" href="http://purl.org/dc/dcmitype/Dataset" property="dct:title" rel="dct:type">Welcome to Your Doom</span> by <a xmlns:cc="http://creativecommons.org/ns#" href="http://megaglest.org/" property="cc:attributionName" rel="cc:attributionURL">Andrew G. Alt</a> is licensed under a <a
rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">Creative Commons Attribution-ShareAlike 4.0 International License</a>.