There have been studies. On one axis the perfect coin-op is trivially easy to get into but almost impossibly hard to master. On a related axis you trade off p

There have been studies. On one axis the perfect coin-op is trivially easy to get into but almost impossibly hard to master. On a related axis you trade off progress/satisfaction vs frustration. In a perfect game frustration at failure motivates the desire to make progress. The game produces just enough satisfaction - likely with intermittent reward - to keep players coming back. Too much frustration and players give up. Too little and they master the game and their quarter lasts for half an hour. The original PacMan is pretty close to ideal. It's immediately obvious what the goal is, and then you slowly understand how the game is designed and start to master each level. Battlezone was a failure, because once you worked out (or were shown) the one trick - dealing with the saucer and missiles by staying in reverse - the game became too easy.