Played this game 2 days ago before the achievements/badges were introduced. Just had to open the game again and play wave 20/20 once, and got all badges at once. You should reset game data, or run a script to erase it locally if data saved already, or even set up another local database for save states.
I just don't understand why 4.48 for a 2D shooter with a metagame inside... maybe ppl here have never played atari before.
Game gets a lot easier as you upgrade weapons, so, not challenging at all. Due lag of lightning and clouds, its even easier to completely clear a wave.
It's about luck. Same bridge isn't working twice on map? First worker can't walk up the ramp is box is rolling (after fall from sky), but the 2nd and 3rd can? Wood not breaking with 3 elephants over it, but steel is? :)