People play video games for different reasons, but I've also noticed that games themselves tend to sit somewhere on a certain spectrum; the reason they're enjoyable in the first place, assuming the game is enjoyable. Most games are about challenging the player in some way, and the enjoyment of the game comes from succeeding at these challenges.
Less commonly, a game may be about providing the player with a unique interactive experience, one which is not necessarily difficult or even challenging, but which is enjoyable more for many of the reasons movies are enjoyable. These may be story elements, audiovisual aesthetics, or interactive touches that don't really provide any difficulty but are fun to see or play with. Together, I call these the "experience", separate from the challenge.
Almost all games have both, and most games tend to have a balance between the two. A game without challenge is potentially boring, but so is game without something to immerse you in. Even the easiest of games usually have some kind of challenge, the challenge just happens to be difficult to fail. Likewise, most games that are about the gameplay and resulting challenge have at least something in the way of changing audiovisuals to keep the player interested.
Take Half-Life 2 for example. At it's core, it's a shooter, and challenge is a considerable part of it. Shooting enemies and trying not to die is a pretty big part of the game. At the same time, it wouldn't be Half-Life 2 without its story, characters, visuals, or even minor diversions like playing with the physics. That last part, in fact, inspired the entire game of Garry's Mod.
Blockland's focus of challenge vs. experience tends to vary. When you're building, most of the enjoyment comes from the challenge, but the experience also plays a considerable part in watching your creation come together. Servers running minigames or gamemodes are almost all about the challenge of defeating other players, but exploring the build and finding secrets, goofing off by yourself or with other players to do something else, or even just enjoying the build for its detail and/or atmosphere all play into the experience. If you enjoy exploring large, detailed builds just for the hell of it, it's for the experience. If that build has traps to avoid and secrets to find, challenge plays into it as well. Roleplay is almost entirely the experience, unless you have some pretend goal and consider roleplaying to get to that goal a challenge.
Whew, that was quite a yarn. Talk about these concepts, I guess.
