This is really beautiful executed! I thought it was reminiscent of 80s arcade games in a wonderful way. The art is great as well.
The controls can probably be cleaned up a bit? Arrows, space to jump, shift+arrows to attack, and Q to switch are a fine enough set. Then you get into E and F and it becomes a bit of a mental load.
Still: I had fun playing. Kid version of me would have absolutely spent the quarter to play again.
I'm not fully convinced you need two tails and switching to make it work. You could just as well have one. And it's weird when they double up for a jump. But that's the premise, and I'm okay being here for it.
Also, dropped a five star rating on the game. :)