I'm sorry for the problem with loading where you end up seeing only the crates. It seems to be random as it only happened on me once. But when it does try reload the page, it should solve the problem.
Thanks for all the feedback so far. I'm glad some people like it. This is just a taste of things to come. I'm working to implement a more features and more level. The end product will be more like RTS rather than just defense.