For the gamers who didn`t beat extreme mode: Spend all the money on laser chain and make a laser rocket first. And when the kills reaches 1100, spam damage exchangers at near of the chains as well as making the chain longer. Please remind that do upgrade the last laser first since it boosts the damage a lot. If the kills passes 2000, sell previous combo and build shockwave quickly then build some tazers at the entrance. After that, continue building the chain and upgrade the laser, finally you find yourself win.
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