The article discusses the design of plasma scenarios for the Spherical Tokamak for Energy Production (STEP), a reactor aiming to achieve net electricity production. The goal is to exploit the inherent advantages of the spherical tokamak (ST) while making conservative assumptions about plasma performance. It concludes that plasma exhaust is most likely manageable in a double null (DN) configuration, and high core performance is favored by positive triangularity (PT) plasmas with elevated central safety factor. External heating and current drive (CD) systems are assessed, with microwaves being the most effective for external CD. Active resistive wall mode (RWM) stabilization and high elongation are needed for the most compact solution. The gap between existing devices and STEP is most pronounced in core transport, due to high normalized plasma pressure changing turbulence characteristics. Plugging this gap requires dedicated experiments and reduced models for turbulent transport. Plasma scenarios must avoid or minimize edge localized modes (ELMs) to meet material lifetime limits. High current for a power plant-relevant plasma leads to high runaway electron beam current during disruptions, requiring novel mitigation techniques. The article outlines the basic design philosophy, major design drivers, and challenges in fully non-inductive operation during the flat-top phase. It discusses the need for novel divertor concepts for plasma exhaust, the choice of NT versus PT configurations, and the management of exhaust. The choice of safety factor profile is also discussed, along with constraints from the HCD scheme and toroidal field design. The article highlights the importance of managing plasma current, ensuring stability, and achieving high fusion power. It also addresses the challenges of non-inductive current ramp-up, avoiding current holes, and balancing conflicting requirements for high-density and low-density plasmas. The article concludes that while STEP presents significant challenges, it offers a promising path towards achieving net electricity production through fusion.The article discusses the design of plasma scenarios for the Spherical Tokamak for Energy Production (STEP), a reactor aiming to achieve net electricity production. The goal is to exploit the inherent advantages of the spherical tokamak (ST) while making conservative assumptions about plasma performance. It concludes that plasma exhaust is most likely manageable in a double null (DN) configuration, and high core performance is favored by positive triangularity (PT) plasmas with elevated central safety factor. External heating and current drive (CD) systems are assessed, with microwaves being the most effective for external CD. Active resistive wall mode (RWM) stabilization and high elongation are needed for the most compact solution. The gap between existing devices and STEP is most pronounced in core transport, due to high normalized plasma pressure changing turbulence characteristics. Plugging this gap requires dedicated experiments and reduced models for turbulent transport. Plasma scenarios must avoid or minimize edge localized modes (ELMs) to meet material lifetime limits. High current for a power plant-relevant plasma leads to high runaway electron beam current during disruptions, requiring novel mitigation techniques. The article outlines the basic design philosophy, major design drivers, and challenges in fully non-inductive operation during the flat-top phase. It discusses the need for novel divertor concepts for plasma exhaust, the choice of NT versus PT configurations, and the management of exhaust. The choice of safety factor profile is also discussed, along with constraints from the HCD scheme and toroidal field design. The article highlights the importance of managing plasma current, ensuring stability, and achieving high fusion power. It also addresses the challenges of non-inductive current ramp-up, avoiding current holes, and balancing conflicting requirements for high-density and low-density plasmas. The article concludes that while STEP presents significant challenges, it offers a promising path towards achieving net electricity production through fusion.