In the three years since Big Walk was announced, I’ve heard it referred to as a co-op walking sim, a puzzle-adventure game, and friendslop. After spending 20+ hours in the world of the Australian Outback-inspired game, it’s no easier to succinctly define it, because it’s not actually like anything else. By inventively stripping down the medium to its most essential parts, it invites novices and experts alike to build it back up from scratch, coloring in its mysterious world with…