More zombies have been killed in the campaign Crash Course than the entire population of Sacramento County, CA, population 1,386,667.
That is almost more than the entire population of Philadelphia County, PA, population 1,449,634!

c9m1_alleys

Difficulty	Playtime	Points (PPM)	Kills	Restarts
Normal	5.68 days	582,755 (71.20)	148,007	1,199
Advanced	2.86 weeks	4,586,129 (158.93)	628,565	5,863
Expert	4.15 hours	26,683 (107.16)	2,766	49
Total	3.70 weeks	5,195,567 (139.33)	779,338	7,111

c9m2_lots

Difficulty	Playtime	Points (PPM)	Kills	Restarts
Normal	2.93 days	276,682 (65.49)	86,640	394
Advanced	2.38 weeks	3,376,338 (140.45)	556,854	4,117
Expert	2.75 hours	52,053 (315.47)	3,747	48
Total	2.82 weeks	3,705,073 (130.32)	647,241	4,559

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