I think you nailed what you were going for and the balance between trying to rush ahead but also take the time to heal is a fairly nice one. The music change was a nice touch too although it was a bit of an extreme shift when you moved up. My biggest concern is that while it pulls off the goal, how sluggish and difficult the game can become isn't always very fun, neither is waiting to let it recharge. I think the idea is good, but maybe the difficulty is a bit too high or the controls just not quite responsive enough for me to push past how uncomfortable the controls feel. But again, I think that does lean it towards what your intention was so maybe that is fine. Overall, creative idea and I think the message is solid.