Both normal and hard badges are quite easy, and the strategy is the same.
1. Build an entire maze only made up by peon towers. Build only one stick man in the middle.
2. Substitute 4/6 peon towers with impact towers.
3. Add in the 6/8 large spaces left by the maze some electric floors.
4. Start upgrading everything, as you wish, of course focusing on the towers near the entrance and near the electric floors.
5. At about level 30, when you have the money, build a boss tower. You should rapidly have large amounts of money, with which you should have in total 6/8 boss towers.
6. Add 3 transport towers at the end of the course.
7. Upgrade everything, adding some impact or boss towers where you have peon towers if you want to.
There is not that much luck involved in this great game, actually. The only two really challenging courses are the last two. In order to beat them with three stars you have to farm some clubs; I actually finished the eighth with 4/5 clubs and the ninth with only 1/2 clubs.
For the final boss: have all the runes, and all the guys maxed out. Then: go after him ALWAYS, and when his shield wears off mash down J/Z and the K skill. Use the L skill (the hurricane thing) only when and if the enemies he calls forth are too many, otherwise keep on chasing him and with some tries you'll get your badge ;).
Took actually three days - some hours of play to get the impossible badge. You have to run for, about, five minutes. It's actually not that hard, you only have to memorize every single sound for the different obstacles and keep trying ;).
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Looks like I just forgot to add it. Will be in the next update, thanks )