In recent decades, there have been advances in the state-of-the-art for simulation of plasma phenomena, from low temperature plasmas for lighting and materials processing, to beams, waves, and other high energy density plasmas. Challenges exist in efficiently simulating transient plasma evolution, where strong spatial gradients and rapid temporal evolution of plasma parameters are not amenable to a singular optimal methodology. Further, current simulation packages do not possess the ability to switch in-situ between fluid and kinetic calculation approaches and are not scalable to massively parallel CPU-GPU architectures. Developing complex plasma simulations, at acceptable computational costs, will enable revolutionary breakthroughs in design and optimization of devices driven by these plasma. IAI has been selected by DARPA to develop a Hybrid Plasma Simulation Tool, or Hy-PlaST, that combines fluid and kinetic models to optimize the computations for speed without sacrificing fidelity. The IAI product will be deployable on massively parallel computing architectures including CPUs and GPUs. Hy-PlaST will facilitate the modeling of complex neutral and non-neutral plasma behaviors involving kinetic, fluid, and radiation transport effects that are common across multiple DoD systems. Hy-PlaST has multiple military and commercial applications, such as modeling of next-generation plasma processing tools and plasma accelerators for applications in the medical and inspection industries.