Hey Ryan! Thank you for your extensive comment and all the valuable feedback you've included.
The game is challenging as is, even for us. So there might be some ground to be gained in terms of balance. At the same time we thought, well "we're generally terrible.. surely other people will be able to come up with much better strategies than us, right?".
Well, turns out that the first step in enabling others to do so would be to explain a bit more how it works. The itch page itself contains most of the explanation so theoretically you could get up to speed there, but it'd still take a couple runs undoubtedly. Tooltips and tutorial to be added, I completely agree.
There is a way to win! The last wave is wave 25, if you beat that then you win. But I'll be honest with you, only Lewl has managed to do so. Myself I've not gotten past wave 14 or so.
The map should expand with 1 ring every 2 waves. And as you rightfully stated, when the zombie reaches the end a necromancer spawns. If the necromancer reaches the end then you've lost. That would be the concept that relates to the theme, where the death of the zombie is the beginning of the necromancer.
All that said and done, thanks again for your extensive response to our creation, much much appreciated!