mhm... the badge with 100kills is quite easy... i upgraded fire rate up to the maximum and dmg 1 or 2 times.. then i repaired after every round my "castle" but after a while i had no more fun and stopped.. had 146kills.
with all upgrades it es really easy.. there are so many ways to reach the 6000 feet.
i used the half power of my rockets at the beginning for a high flightlevel and tehen after a few thousand feet i used the rest to get new boost and more flightlevel.. you should try to keep your speed and not to loose to much fligtlevel. so it should be easy.
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