Why all these spam comments? Anyway, after each upgrade they should have the appearance change slightly. This isn't something huge but something as small and little change as that will make a huge difference to the game play to this game. Why? Simple! I'm always going to wonder what the next upgrade will look like! Therefore, putting more hours into the game.
TIP 1: Upgrade your towers during a mission!
TIP 2: Only use first 2 towers threw missions 1-10
TIP 3: Don't upgrade the first 2 upgrades before u start a mission. Save up to 20 for the 3rd upgrade.
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