Remember that whole argument we had over Pluto a few years ago? That was caused by a lot of little factors, but a big reason for the confusion is that we were all using a word and we mistakenly thought we agreed on what it meant. It turned out "planet" meant different things depending on who was saying it. When we finally nailed it down, people became upset because the official definition didn't match the definition they already had in their heads.
Another disputed word lately is "videogame." We've used the word for years, and we've always assumed that we all agreed on what a game was. Then something strange and experimental comes along like Loneliness, which doesn't seem like a proper game to most people, even if they have no idea what else it should be called. Even the author refers to Loneliness as a "notgame." There are a lot of indie titles like this, lurking on the edges of the hobby and challenging us to question what games are, or can be. Dear Esther is another mischevious title where it looks and sounds like a game, but doesn't seem to meet our expectations of how games ought to behave.
The troublemaker lately is Proteus, a game about a procedurally-generated island of lo-fi graphics and haunting music. There's no explicit goal, no enemies, no score, and no extrinsic motivation to do anything. No story, no dialog, no characters, nothing to build or destroy, and nothing to acquire. You don't even have a button for interacting with the world. All you can do is move around and look at things. The music changes based on where you are. There are sometimes standing stones that ring out a musical note when you pass them, but since you're not rewarded or penalized for any of it, is doing so really considered gameplay?
Is Proteus a game? Some people say it can't be a game, because you can't lose and you can't win. The game does sort of end, its up to you to decide if that's a victory condition. If it's not a game, then what is it? Does something need explicit win or lose states to be a game? What if Proteus was changed so that you could die if you fell off a cliff? Would that make it a game? What if we added a pointless leveling system where you gained XP by visiting locations and looking at them? Now is it a game? What if we gave the player a score at the end that told them how many different standing stones they visited? Is it a game yet?
Videogames were forged in the 1970's, in a world of smokey, lurid, coin-operated arcades. They sat beside skee-ball machines, pinball machines, and cigarette machines, and they had the same purpose: They were designed to eat your money. The game over screen was there for economic reasons, not because the public had an insatiable demand for games that ended. When consoles rose to prominence in the 80's, they began as blatant and unashamed copies of their arcade forbearers. There was no reason they couldn't have open-ended experimental gameplay except that people didn't think of games in those terms yet.
Eventually we broke free from the coin-operated arcade paradigm, but everyone was still fixated on win/loss states. In text adventures, you played until you won. In almost everything else (Asteroids, Space Invaders, Pac-Man) you played until you lost. You never just played.
While probably not the first open-ended game, the first SimCity (1989) was wildly popular and radically different from the things that had come before. At the time, people were puzzled over this new thing, a "game" with no explicit conditions for victory or loss. Trying to explain his invention to the confused masses, designer Will Wright called it a "Software Toy." Nobody seemed to notice that the term "Software Toy" applied not only to this new Sim thing, but also to every single game that had come before it.