Hahaha, thanks. Funny you should say that, around halfway through my attempts on level 6 I thought I should be due a cash reward. Then after a while it suddenly clicked and I got into a weird flow where I didn't drop gravestones on my gravestones or drop them onto the bullet spawners.
I'm sure there's a market for this game. I'm also rather happy my old ass can still handle this sort of twitch gameplay lol.