I apologize for not realizing how easy it is to beat the last level in under a minute. Don't block the lazer and just keep hitting the mega tank while it's vulnerable. If you upgrade everything this works amazing.
level 15 in under a minute and a half is impossible. Even destroying the mega tank in under a minute and continuously destroying everything as it came out didn't work. has anyone managed this? HOW?!
The game is not refined, but I love the in depth strategy gameplay. I recommend better movement and soldier control. It is very clumsy. Maybe take a look at Company of Heroes to see how it's done.