I have the exact same problem, here's what I do.
Finish the maps in the order of coolest and most finished, to not-so-coolest and least finished.
I have Light in the Darkness RPG (almost done!!!!), then I'm gonna make the combat-system based Demon Dragon's Voice RPG, then finish Elemental Dragon Wars, then Mechwarrior RPG, then my Doom RPG, then Elemental Den Defense, then Pirate Islands (like Space Pirate RPG, and zone control together, with a special combat system, it's by far the most daunting map I'm making), then finish Element Dragons RPG 4 and 5.
The Elemental Dragon stuff are the clan maps I'm making. So all in all, it's about 9 maps in the works
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