Suggestion for a tweak: make the visible injury based on a percentage of damage taken rather than the current HP, first half of the waves look like their composed entirely of zombies.
The 'check my work' button seems to only show conflicting entries, not deviations from the solution. There is often more than one solution set that will fit the fixed numbers without showing as having any errors, but no 'clean run' if you use the wrong one, and there's no way to tell which one is right except by looking at the solution, which also means no 'clean run'.
 "Drill Baby Drill"){kind=icon}
 "Friendly Fire TaD"){kind=icon}
 "Drupple Sudoku"){kind=icon}
 "Back2Back"){kind=icon}
 "The Last Village"){kind=icon}
 "Speedway Tower Defense"){kind=icon}