[The second in Gamasutra's 'Game Design Essentials' series, following '20 Difficult Games', looks at the roots and design lessons of 'open world games' - titles in which the player "is left to his own devices to explore a large world" - from Adventure through Metroid to Grand Theft Auto.]
When we discuss "open world games" in this article, or sometimes "exploration games," we mean those games where generally the player is left to his own devices to explore a large world. What all of these games share is the seeking of new, interesting regions at whatever time the player deems fit. No force forces the player's motion into new areas. There's no auto-scroll, and there are no artificial level barriers.
A couple of games, such as Air Fortress, push this by offering many mazes, but they are more like many individual games than one large map. One of these games, Cadash, is presented for contrast, but technically fills the description. Most of the games take closely after Metroid games, or are one of them. Fully half of the games here contains substantial side-view platformer elements.
At the core of the open world game is consumption. Once a place is seen for the first time, it cannot be unseen and seen again. To an extent, the game is a maze, and once the whole thing is seen the game cannot be played the same way again. Perhaps it can be played for a good score or a good time, but that's a substantially different kind of experience.
Some games attempt to offer replayability through randomization. Roguelikes and strategy games in the mold of Civilization do this. Some allow the player's state to vary, allowing them to reach a given point in the game world in a variety of ways, each with its own implications for the situation found there. However, no game in this list uses randomization in this manner.
Some particular comments on the games that were picked for this list:
1. As with all such lists, some things had to be left out. Morrowind and Oblivion are particular games in which exploration plays a prominent role, and their absence, or that of any other game, should not be taken as a slight against them. There are other reasons they are not mentioned here, one of them being that I think it's best to possibly save them for a later article on RPGs.
Also notably absent are any adventure games, either textual or graphic. This is also not intended to short that genre. Also missing is the notable Commodore 64 game Phantoms of the Asteroid, but it was covered last time. Another Commodore game that could make the list is Spindizzy, but the fact is I don't think I have enough experience with that game to write well about it.
2. As with the previous article, 'Game Design Essentials: 20 Difficult Games', this is not intended to represent the best open world games, or the ones that are most "explore-y," although some of them are pretty nice. The games are chosen for their instructive qualities and general interest, not to compare them using a meaningless yardstick. They're here because I could illustrate something important using them as examples.
3. Some out there in Internet Land snarked, concerning the previous list, that it was biased towards older games. Yes it was, and I make no apologies. Older games tend to have more elemental designs, presenting their mechanics strongly rather than submersing them between a sea of what a game is "supposed to be." This is particularly useful for explaining and highlighting design conventions.