Energy storage is one of the big challenges for the energy transition and ammonia as a hydrogen carrier is considered a promising candidate for efficient and medium- to long-term chemical storage. Gas engines are well suited for power generation using ammonia as a carbon-free fuel, making it unnecessary to convert ammonia back to hydrogen for the utilization in the power plant. This study investigates operating strategies for a prechamber combustion concept for a large-bore gas engine suitable for power generation applications. To overcome the high ignition energy and low laminar flame speed of ammonia, different quantities of hydrogen as a promoting agent to improve the combustion properties of ammonia have been employed in the experimental investigations on a single-cylinder research engine. The combustion concept shows a wide operating range with stable and robust combustion from 0.3 to 2.5 MPa indicated mean effective pressure and will be transferred to a multicylinder engine for the first combined heat and power demonstration.