Zombie vs Human, they both have brains (neural networks), humans got a gun, zombies got the numbers.
Zombie reproduce by eating (touching) humans, which in this case die. They die by starvation after a certain time.
Humans reproduce if they reach the end of the night (again, fixed amount of time). The survivors go to "sleep", if you know what I mean, and reproduce.
When a zombie reproduces, they clone themselves into the killed human, plus some random mutation.
When humans reproduce, they mix between males and females, plus random mutation.
By mixing/cloning we mean that they share the same brain between generations. Other stats may be forwarded as well on a later stage, like speed, perception radius, shooting speed.