This game sucks especially because the alleged "upgrades" speed and range actually make you worse AND you can't sell them - it's kind of addictive which is weird.
Once piece of advice for challenge mode: 10 damage seems to be the magic number (i.e. where the damage is evenly divisible by the creeps life), try to rush for that
no badge = sad
Note to Kongregate: if you want to encourage games to be played with prizes, perhaps the draw entering system should be tested at some point.
To beat the concrete thinker part (if it doesn't bug for you) the idea is to not get your mouse hit by the boulder or hit the walls. just move your cursor leftwards off the screen at the beginning
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