Not sure what you mean by this
This sadly limits the maximum amounts of hearts I can have to the size of my sprite :/
This tutorial shows the method described by kraed
https://www.scirra.com/tutorials/565/be ... -indicator
Another idea is to stay with your original method, but to answer the question
But how can I remove one heart when the player dies? How do I know which one to remove?
you can do:
System: Pick sprite instance sprite.Count - 1
Assuming they are displayed in the order they were created in (might need to re-order them first).