There stamina system which affects maximum jump height, which doesn't take effect while Nemo is healthy because the regen speed is too fast, but taking injuries, soul damage, or fatigue will reduce maximum stamina and stamina regen at varying rates, and this affects jump height. For instance, being cut with a sword reduces max_stamina but doesn't affect regen at all except from blood loss, while burns and broken bones will make Nemo get tired easily from running and jumping as well as swinging her sword. There's no way to treat injuries right now, but I'm working to make the game not kick you out so much as take you somewhere new.
You also have to hold both the jump button and upward movement direction to reach the highest apex, and you can't jump while stumbling, which happens when you hit the ground hard and slide causing dust to appear by your feet.
While jumping or sprinting there's a short cooldown between moments of acceleration, shown by the "STEP" sprite coming out of Nemo's feet, which the animations sync to.
And flight is on a cooldown shown by Nemo's wings turning black.
AAAAAaaaaaa why did I make it like this? Thank you for trying my game.