I haven't played the games this was inspired by, and I don't think the rules are apparent at all without that background. Maybe explain them a bit more.
Recommend improving the controls in the following ways: Characters should swap when a character is dragged onto another character. Characters should drop onto the location where the mouse pointer is, not the drop shadow. I can figure out that they're being dropped at the dropshadow and that's the reason a lot of my drag actions are being ignored (that's how it feels before the player realizes what's happening, like inputs are just randomly failing), but aiming with the shadow of the thing I'm dragging instead of the mouse pointer feels wrong.