This document discusses the application of the Runge-Kutta (RK4) numerical integration method in game physics simulations. RK4 is a 4th order method that calculates estimations in 4 steps to provide extremely accurate solutions with less risk compared to previous methods. It is commonly used to model rocket trajectories and sniper shots in games. While more complex to implement than other methods, RK4's increased accuracy rewards it with more realistic in-game physics simulations and fewer bugs.