You get access to run after you beat the first special stage. I thought the same about the advanced towers but after a while I realized the game would be too easy if all the towers you unlock on one stage would stay unlocked. On +10 wave stages its easy to have up to 45 gems per map. You'd have multiple maxed out morter, laser, and hive towers. That wouldn't be fun. There is actually a map that starts with access to all towers and a lot of currency. It was too easy (constant flood of monsters of different types, and two final bosses).Originally Posted by Pyro
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