Obstacles should never be missing from your playground. You are spoilt for choice: walls, hedges, fences, sandbags, barricades, piles of wood or stones and much more. Obstacles, however, are double-edged swords - on the one hand they offer protection and cover, on the other hand they stand in the way of the troops and thus prevent quick progress... but that's exactly the point. but that is exactly the point... If you choose and use them strategically, they can tip the scales and decide the game in your favour.