This is not a metroidvania, as you get no actual upgrades, such as... i don't know, how about stronger weapons not at shops? And unlike Castlevania, you only get one stat for each level, making leveling no help whatsoever. You have to pay for that, and this is a freaking flash game. FLASH. Really now, thats as pointless as paying for this is the only level. This company should accept tips, not force you to pay.
badges badges badges badges badges MUSHROOM MUSHROOM!
So let me get this; you upgrade towers and kill bloons, which allows more upgrades, so you can upgrade to upgrade more. So simple!
after about 6 million feet, this gets (sadly) boring. The soundtrack and stuff are epic, but it wears off. Just to let ya'll know, i played this since it came out :P
 "Continuity"){kind=icon}
 "Ghost Guidance"){kind=icon}
 "Remnants of Skystone"){kind=icon}
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 "DuckLife"){kind=icon}
 "One Button Bob"){kind=icon}
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 "Fly Hard"){kind=icon}
 "MoMiner"){kind=icon}
 "Level Up!"){kind=icon}
 "Ge.ne.sis"){kind=icon}
 "Crunchdown"){kind=icon}
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 "The Visitor"){kind=icon}