It's not exactly a game industry-oriented token like GameCredits. PLY tries to revive the concept of proof-of-play, which was implemented in Huntercoin and Motocoin. But this token takes it to the next level, as it removes hurdles of being a mining machine (because the blockchain is already protected by Ethereum) with all its implications like difficulty competition. So it works more like proof-of-play-distribution. All game states are stored forever and can be used as fingerprints to prove the consistency of distributed shares. Another use case could potentially be an adoption by board game associations.