To review from Part 1: Plato valued absolute truth, irrespective of player preferences, and so he argues that good games come from good developers. Aristotle had a slightly more pluralistic account of truth that was player-dependent, and so he argues that good games come from good players - and "good players" are skilled players who can beat difficult games.
For Part 2, we'll derive some additional philosophies from Aristotle's account - some more modern, mainstream player-centric theories that are all the rage right now.
But first, some history that's crucial for understanding those approaches:
In 1982, Atari had a wildly popular videogame console in the US, but didn't regulate who could publish games - so in 1983, the industry crashed from the collective weight of so many poorly designed games made by pet food companies and other ilk. Gamers have never forgotten: We're obsessed with whether a game is "too short" or if it was "worth it," and videogame reviews, unlike their literary, music, film, and art counterparts, routinely take price into account.
So now we quantify: How many weapons, levels and hours of playtime? You could only fit so many levels into the limited memory of an NES cartridges so developers found other ways to inflate playtime - Mega Man reuses levels and bosses in more challenging ways, Final Fantasy recolors enemy sprites for more powerful variants - because a more difficult game took longer to beat, which in the end was a more "valuable" game.
But, as we mentioned before, relatively few people have what it takes to master videogames: Namely, enough disposable income (or allowance) to pay for these games and several long, uninterrupted stretches of free time to master these games, not to mention a whole lot of luck, skill and perseverance.
Such people were usually middle-class teenagers, the source of the "gamer" stereotype that's thankfully dying today. While these gamers had internalized the crash of 1983, so had the industry. They sought stabilization though stringent quality control, an emphasis on general "entertainment" (e.g. "wow, the PlayStation 2 plays DVDs too!") - and more recently, by expanding their audience through accessibility.
All modern player-centric design philosophies re-cast the "good player" - from the classic Aristotelian notion of "skilled player" to "every player."
Now as philosophers, we have to ask: What does it mean to be accessible?
For one sense of "accessible," perhaps we can take the release of Valve's FPS puzzler Portal as a watershed moment in this field.
Portal defined accessibility as "almost anyone can play and beat this game." It was rather short, yet few complained about its length. (It was also part of the Orange Box, a collection of five games for $50 that utterly exploded our collective notion of value.)
While accessibility had been an industry concern for many years leading up to the game's release, never had it been so fundamentally integrated into public accounts of the development process. Much of the press and interviews focused on how frequent testing decided which puzzles to keep and which to reject.
This emphasis on collecting data - most often quantitative data to balance multiplayer games - is an empirical approach to game design. Here, accessibility means posing a hypothesis ("If the build time for a Protoss Zealot is longer, it will balance early game harassment.") and collecting evidence to confirm or deny that hypothesis ("Protoss are now winning fewer matches under four minutes in the Gold league.").