FroggieG, I know reply comes late, but you have to touch zombies with the mouse pointer in end screen to make them explode. No mouse button clicks needed. If one slips through and touches the ground, counter goes back to zero. For me collisions registered well and it was easy under 30sec job to do 10 kills. With a little practice, i got 27.
For fellow badge hunters who are not fans of this game series:
1. Open the game window and walkthrough window side by side
(or use other tab/window to swap with)
2. Keep the "Page down" key pressed until nothing happens
3. Click what the walkthrough says and go to step "2."
4. You got badge easily in about 10min, no need to vote 1 star because some people like these games.
I used this:
https://moshimushi.net/2019/09/04/medieval-chronicles-the-paradox-walkthrough/
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 "Flaming Zombooka 3 : Carnival"){kind=icon}
 "Gravitee"){kind=icon}
 "Medieval Chronicles 5"){kind=icon}
 "Mine of Sight"){kind=icon}
 "Flight"){kind=icon}
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