The challenge graves in Knie Tief may or may not be broken.
The triggers to use them are very small and are painful to use in higher rounds. The Brawlers also drop two max ammos, and I can't really find a way to activate PaP. Maybe I'm not looking hard enough? Nonetheless, I find Knie Tief to be very fun and I look forward to more maps.
edit: btw i just got a g_spawn from using the AA-12, fyi kek