I have really enjoyed it. You have to place defence weapons in the path of the armies that are coming to your base. You must stop them at all cost. You get money to upgrade your weapons and research. It was really hard at first, but I learned to adapt to it. I haven't beat the hardest map as of yet, but will keep trying until I do.
Below is a picture of my last level. It shows me using all the upper cannons. They cost 1500 a piece. I also put the score in the picture.
Here is a link to the game FWG Random Defence Game