There are many things you can do with this theme which is great

The word "Sacrifice" made me think about magic hmm...

I have come up with some ideas:

• You can make an amount of health and make sure that if a player uses any attacks they will lose health like Nicromancer Magic

• Or Make it as Energy like on a spaceship and it stops moving of you don't have any left

• Others

I think it would be interesting to ge with the spaceshipt idea and make it so you have to balance moving around and shooting and to not use all of your energy