I really did find this to be a great game! It's mostly because this is a truly original idea! I can't think of any other game that has done this. It's great that you show off such creativity. The best thing is probably how you can just create as many obstacles as you want. While the graphics aren't that good, the gameplay more than makes up for it.
It's great to see how far away you can get your opponent. I was confused as to why you couldn't place some down. That's because they completely blocked the enemy's path! It's nice to just see them scurry around. This was great, IMHO.