I think that it would be quite interesting if you (being the player) could test your own base defenses (or fleets for that matter) with your own fleets. As in instead of sending out your fleet to attack other players, you would in essence attack yourself, and then you could watch and learn a better strategy from the proceeding battle. Perhaps you could also send your different fleets against each other.
I suppose it's optional if any destroyed fleets stay destroyed and need to be reconstructed, but they don't have to be.
I think there should be an option where you can set the aim of the Dartling Guns so it points in one direction (not towards your mouse but not specifically aiming at the bloons) while you can then purchase upgrades and different towers.
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