For about 15 hours and 57 minutes of our 16-hour playthrough of Big Walk, my kids and I laughed as we stumbled down cliffsides, put our heads together to solve dozens of inventive puzzles, and rejoiced whenever we’d finish a task and that small burst of confetti would shoot out, unlocking our all-important “eggy things” we’d need to beat the game. That experience already made Big Walk one of the best co-op games I’ve ever played. But the final three…