Sniper Elite v2

The Truth About Guns reviews a video game called "Sniper Elite" version 2:

[In the game] you play as an OSS Secret agent inserted into Berlin during the final days of World War II to stop the Soviets from obtaining some deadly new technology. Your targets are German V2 scientists. 

... Sniper Elite V2′s claim to fame is its new X-Ray Kill Cam. This feature shows the damage a round from your rifle does to an opponent with gruesome detail. The camera doesn’t activate during every kill, only those that require significant skill to pull off. This is made vastly more difficult by Sniper Elite’s inclusion of bullet-drop and windage.

Much like in real life, bullets don’t travel at the speed of light (yet) and are affected by wind. What this means to the player is that, based on his wind meter and the range to target, you have to utilize the mil dots on his scope to compensate for the ballistic trajectory of the round. That makes you really “earn” each kill unlike more mainstream games like Call of Duty which utilize instant hit-scan projectile tracking.

I know its not a zombie game, but any game that attempts to accurately portray ballistics may be worth a look.