$K^+\rightarrow \pi ^+\nu \bar \nu $ Decay and NP Searches at NA62

The decay $K^+$ $\rightarrow$ $\pi^+$ $\nu\overline{\nu}$ with a very precisely predicted branching ratio of less than $10^{-10}$ is one of the best candidates to reveal indirect effects of new physics at the highest mass scales. The NA62 experiment at CERN SPS is designed to measure the branching ratio of the $K^+$ $\rightarrow$ $\pi^+$ $\nu\overline{\nu}$. In 2016, the first data set good for physics has been collected. The preliminary result on BR($K^+$ $\rightarrow$ $\pi^+$ $\nu\overline{\nu}$) from the full 2016 data set is presented here. Due to the high beam energy and hermetic detector coverage, NA62 has also the opportunity to directly search for a multitude of long-lived beyond- Standard-Model particles, such as dark photons, dark scalars, axion-like particles, and heavy neutral leptons. An overview of the broader NA62 physics program with status and prospects will be illustrated.