Thanks for playing! The concept is that you are constantly losing health, you use right click to possess an enemy that is a green "target" (e.g. less than 50% health), thereby refilling your health. The itch page for the project has more information for this and the controls. Hope you give it another go :)
Thank you for the reply and letting me know where I was going wrong. I did indeed have another go, and made it up to wave 9 a couple of times, but that's suddenly a lot of enemies on the screen! Fantastic premise too, I'd love to see some enemies that couldn't be taken over, or others with different abilities in the future. A great little entry into the Jam, and I've amended my rating to reflect the fun I had!