It's a wall with electrified spikes on top. And armed guards instructed to shoot on sight. And rabid dogs. And behind the wall there are other walls.

I tried to start the game 5 times. The first 3 I could not even start a game. The 4th one I followed a tutorial and was able to start, and nothing else. The fifth time, I found Captnduck's excellent video tutorials ( http://www.youtube.com/watch?v=koZUS2h-Yzc ), and I was finally able to break into the game.

Then they added a whole layer of complexity to the military (with a lot of new UI quirks) and I just stopped playing.