This is unique.
You could make it even more so by adding a few more mechanically unique entities, like a creature that disables your eyes for a moment and one that damages your eyes somehow, so it could potentially destroy some of them.
Then you could add different challenges that make it much more interesting and incentivizing to keep playing. Stuff like “use only X towers” where X could be multiple levels of progressively less towers, say 10 -> 5 -> 3 -> 2 -> 1. Or “never upgrade a tower”. You could even make it so when you die, you get a card certifying all challenges that you achieved and how far you got (wave number).