MiniHack the Planet: A Sandbox for Open-Ended Reinforcement Learning Research - Samvelyan, Mikayel; Kirk, Robert; Kurin, Vitaly; Parker-Holder, Jack; Jiang, Minqi; Hambro, Eric; Petroni, Fabio; Kuttler, Heinrich; Grefenstette, Edward; Rocktäschel, Tim (Proceedings of the Neural Information Processing Systems Track on Datasets and Benchmarks, 2021)