The Terror of Choice

As I sat at my desk sketching out a puzzle structure for my next game and listening to the latest episode of Radiolab, “Choice,” I started to think about complexity in goal trees. Just about any game’s structure can be represented as a tree (a partially-ordered set, really) of goals, some of which are required before others.

For the simplest of games, this tree consists of a straight line of nodes labeled something like “Reach Checkpoint 1,” “Reach Checkpoint 2,” and “Beat Boss.” Games with a hint of nonlinearity, however, can often have rather complicated goal trees. The simple tree has a branching factor of one. Each action, or node, has only one successor action. The game Planescape: Torment, on the other hand, has a branching factor of more than ten in some places, such as just after the player reaches the Clerk’s Ward. There are many the player can go or quests she can pursue, each separate and rather complex in its own right.

I’ve been playing The Elder Scrolls IV: Oblivion lately, and that is a game with a branching factor. Each town has four or more quests connected to it, in addition to the main quest, which itself sometimes branches into subquests. Add to this the guilds, of which there are at least four, and the game gets a bit intimidating for me. I hesitate to even mention the plugins and expansions. I walked through the door to the Shivering Isles, a whole new country with its own central plot, towns and sidequests. I think I lasted about fifteen minutes before I retreated back to Cyrodiil, overwhelmed. Oblivion‘s branching factor is a bit too large for my tastes. So what, then, is the optimal branching factor? Let’s look at some examples.

The Lucasarts adventuring standard is three. The Secret of Monkey Island opens with a search for a treasure to find, a valuable to steal, and a sword to master. In Full Throttle‘s Melonweed section, Maureen needs forks, a torch, and some gasoline. Your typical work of puzzle-based interactive fiction will be more complex; just wandering around for a bit at the beginning of Jon Ingold’s “The Mulldoon Legacy” yields at least five interesting and tricky set pieces to play with. Cognitive psychologist George A. Miller determined that the human mind can hold about seven things in memory at once, although it’s arguable how much that research applies to complex tasks like goals in games. Regardless, I think expecting a player to remember more than seven goals at a time is terribly ambitious.

So what’s my opinion? It depends. If the player must keep everything in her head, I think any more than three goals at a time is asking too much. Given an in-game journal or objective list for tracking goals, however, I think that number can increase. If the goal-tracking system can be sorted by time, type, and geographic location, a designer can get away with a rather large number of goals, as the player’s mental capacity is enhanced by the reminders in the game.

What’s your opinion? How complex can a game get before you begin to feel overwhelmed? What’s a game that you’ve played that is too complex? What about one that handled complexity well? Let me know in the comments.

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4 thoughts on “The Terror of Choice

  1. I didn’t really think that Oblivion was “too complex”, but I can certainly see your point. It really is pretty easy to get sidetracked to the point that the main quest gets bumped to the bottom of mission priority. Fallout 3 is similar in style, but side missions aren’t as easy to acquire. Including exploration as a quest, though, can lead to some long gaps in between bouts of productivity. In these cases, returning to the main quest after a long hiatus creates a certain disconnect with the story and can spoil that part of the game.

    Assassin’s Creed, in the spirit of newer titles, gave an illusion of choice with choices of targets, each with 9 information gathering missions to choose from. The variety was stale before too long, and the choices didn’t seem to make much difference when you opted for completion. It still had a sandboxy feel, but it never really had enough branches that mattered.

    I really think that Grand Theft Auto III had a very good balance of side quests, item hunts, and main missions without providing too many branches to get lost. Furthermore, it restricts gameplay in stages giving the player reason to make certain levels of progress in the main quest(s) to allow greater freedom. I can’t speak so much about GTAIV, though, as a) I haven’t played enough of it and b) the incentives from GTAIII simply aren’t present in the sequel.

  2. I don’t think Oblivion is so complex that it hurts the game. It’s just too complex for me personally to pursue the main quest, the Shivering Isles quests, and the side quests at the same time. It has a decent quest record system, although I’d love to be able to sort by geographic location. My biggest issue with Oblivion‘s breadth is that the main quest seems much more urgent than, say, Morrowind. I feel kind of weird trying to join the Mage’s Guild or outfitting my pirate base when there are demons pouring out of portals outside several populated towns and the empire’s threatened by an evil cult.

  3. I always found the lack of personal urgency in Oblivion to be amusing up to a point. Once again, though, it establishes a disconnect particularly in quests where someone is supposedly in grave danger. You take your sweet time getting around to it only to find that they are no worse off after several in-game weeks.

  4. I like how an NPC will say he’ll meet you at 8:00 PM in place X, and it’s clear that he proceeds to show up every night exactly at 8 and hang around for hours waiting for you to show up before going home dejected.

    Every night. Until the end of time.

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