Alright, I finally had my chance to take time to test your game. I really loved it! Like many comments here the level where you're forced to swap blocked me but then I read the description and bam, solved!
It reminds me a lot of "Into The breach" were you are outnumbered but you have the advantage of knowing your opponent behaviour. I would have loved some indication on their next move eventually, the biggest challenge they had for ItB (visually speaking).
Maybe swapping to anything you want without any trading is a bit too open, I would suggest a maximum distance or a cost (energy that could recharge). That will force you to create more interesting scenarios for your LD, as you're going to close options. Here, knowing that the player can swap whenever he wants to to any enemy will stop you from controlling the level design. Think about simple rules that could improve that "control".
The difficulty curve was not bad, but there is room for improvement for sure.
The only "bad" point for me was the theme, it's close to "one single player game", like any single player game that could pretend to match the theme. It's more than that but I've seen more original ways to represent the theme.
Overall very good job, this is a very polished and pleasant experience, I would like more!