The US Department of Energy’s (DOE’s) Office of Advanced Scientific Computing Research (ASCR) is tasked with supercomputing, high-end computational science, and advanced networking for science. One of its most important tools in advancing computational science is the annual ASCR Leadership Computing Challenge (ALCC). The competitive program grants 1-year allotments of high-performance computing (HPC) time to scientists from industry, academia, and national laboratories whose work advances scientific and technological research in DOE mission areas, such as fusion energy, geosciences, high energy physics, and materials sciences.