@Vidd: yes; just go to it's little upgrade screen and you'll see the rotate button next to name and rank.
Beware, though, the wall has to go back to the unit bank after doing so, so make sure you have room for it.
What i really love about this game is not the variety of units, the graphics, or the many things to do, though they are all great; it's the challenging, yet fair bosses. Few things give more accomplishment than taking down those large ships,which will devastate your towers if you give them the chance.
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