how do you kill those dang auto repair units???

Why do you have to beat all 3 levels of difficulty before you can open up new levels? It took me forever to get past the easy level (obviously I'm not a talented gamer) and I was very happy that I'd finally managed to get through it and would be able to move onto the next level. I may as well uninstall the game because I don't have a hope in hell of beating the hard level. If you are reading this developer can you please explain why I can't play the entire game on easy mode?...

Struggling on "easy" and finding some units are getting through without damage even though I have an upgraded Radar Tower. Any ideas?

Just curious how others are getting past the first map. No matter what configuration of weapons I use, I cannot get past wave 30. I've spaced evenly. I've spaced far apart. I've used clusters of gatlings, used clusters of rockets/SAMS, clusters of lasers...I've used walls, I've used invisible detect, but I can NOT get past level 30 for some reason. Any help in this is appreciated. Thank you....

Hi, Been playing this game for months now (not my copy) and presently at The Tundra level, Hardest Difficulty. So far I can only reach level 47. When I first started playing I was extremely frustrated that you couldn't get to the next section until you completed all difficulty modes. However, out of pure bloody mindedness on my part I persevered and gradually managed to work my way through to where I am now. There IS an enormous amount of satisfaction when you do complete a map, but there is also a huge a...