To beat the last level use your fortress and the planet closest to it to capture the shooting thingy. Then capture the yellow fort by shooting your blue particles at it. Do not use the particles from the 2 closest planets to the black turrets as it leaves you open to attacks. Then capture all the yellow planets and start storing particles in the shooter. To win just use all your particles and shoot it into the black centre thingy. I used about 200+, but less may suffice.
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 "Infectonator 2"){kind=icon}