edit: I'm sorry I'm a bit tired, this post is needlessly critical. The idea of the paper is fun, and can serve as a source of inspiration for good thought, I my

edit: I'm sorry I'm a bit tired, this post is needlessly critical. The idea of the paper is fun, and can serve as a source of inspiration for good thought, I myself have enjoyed thinking about proof-of-play for a long time and I still hope I'll think of a way to make it work some day. (/edit) This system is in no significant way distinguishable from proof-of-work systems. Unfortunately the only 'difficulty' introduced here is that the computer has to interact with a physics engine. There's a lot of claims made in the paper but no references to any scientific research. Some examples: The article claims playing the game is hard for a computer, but never says how hard precisely, what's the complexity? The article claims games exist that are easier to play for humans than they are for computers such as Go, obviously for Go this has been shown to likely be false the past week, but also in general. Are there really games that are hard for computers but easy for humans? I played with the idea of a game-based cryptocurrency, as the basis for a MTG like economy in a roguelike game, but failed to come up with any mechanism that would be easier for humans to play than computers in a fundamental way, but I didn't get so serious as to look up scientific work, and neither has the author of this paper. The article claims that should a bot arise that can beat this game like humans can, they can simply increase the difficulty. Can they? he didn't calculate what effects the variables of the game have on the complexity. Who says that if the game becomes more difficult for computers, it is still playable (let alone fun) for humans?