Thursday 30 August 2012

zaga, score, expressivity, personality

Came across some brief discussion of Zaga-33 in the comments of this auro post while browsing google searches trying to figure out what had triggered a bunch of sales (I know, pretty sad). Padi and Keith make the point that there's limited scope for really expressive skillful play; we discussed this in the roguelike radio podcast as well.

I do agree with this; although there is room for skill in the game, there is a ceiling which can be reached. You can get to a point where you've fully mastered the game: you can complete it 95% of the time, get the maximum score, get the secret ending, whatever. It takes some time to get to that point, most people won't, but once you're there there's little reason to play again. It's not a game you can spend your whole life getting better at. And that's okay, it doesn't need to be, but let's think about why.


The scoring is something they mention as limiting Zaga-33's scope for virtuosity. And I think this is an error, in fact I believe the opposite. When a game (or anything) does a few things differently to usual, we tend to latch onto those differences as an explanation for anything about it; I think that's what's happening here.

Score is a measurement we take of a game system, ostensibly to evaluate how well a player performed. We tend to design scoring in parallel with the rest of the game, but it's a one-way interaction, strictly an output. It doesn't affect the system, it's not a resource to manage or whatever, it can't add any systemic depth to the game. It can reveal depth that was already present but not apparent, but it has to be there in the first place. So the fact that the score ceiling is accessible - well, that's an effect of the skill ceiling being accessible, not a cause.

Super Crate Box awards points for collecting randomly located crates which randomly change your weapon. Some of the weapons are terrible, or only situationally good, so improving your score can put you in a risky position. The developers joked about changing the game to award score for kills rather than crates, apparently this was somehow a common suggestion from players? That's a very uninteresting way to play; once you have a good weapon you can sit in a corner and safely rack up any number of kills, getting an arbitrarily high score without risk. However, there's nothing to stop you playing in either way regardless of how it's scored! Even if the game counted number of kills you could still perform the exact same actions as if it was counting crates and presumably enjoy the game just as much; the scoring simply provides a guide towards an interesting way to play.

In a multiplayer game we typically take a binary measurement: win/lose (although sometimes we allow draws or care about position e.g. in the context of a tournament). This is often appropriate in a single-player game, especially if there are other limitations on replayability (e.g. fixed story and content), but in a game that's meant to be played repeatedly, it's more satisfying to take a higher-resolution measurement of performance to provide goals and a sense of progression. Because your opposition is a fixed algorithm, there's a certain level of performance required to reliably achieve a binary "win" measurement, after which there feels like little reason to keep playing and before which there can feel like little progress. Again, there's nothing to stop someone playing a game repeatedly regardless of scoring, it just provides guidance towards an interesting way to play.

(Note that multiplayer games sometimes have a score value which is measured and compared to determine the winner; this is conceptually quite different to how single-player scores operate because ultimately all that matters are the relative values, scores are not comparable between separate plays of the game.)

When measuring a score, we typically throw away a lot of information about the game (we could encode all information about its state and history in a single number but this would be highly atypical). So there's a question of how much we want to throw away, what resolution to measure at. Zaga-33 has a fairly coarse score: one point per level, and one for each item when you complete it. Does this coarseness limit the game's expressivity? I don't think so; it actually increases it. See, the more precisely a score measures your performance, the more precisely it specifies what counts as a good performance. This reduces choice by dictating how you're expected to play. A score that throws away a lot of information allows players to more freely choose what that information is. This doesn't mean that it doesn't matter what you do: skillful play will get you further by conserving resources, resulting in a better score overall. But it means your actions are dictated less by details of the score and more by complex evaluations of the entire game state. It takes more skill to evaluate and manage resources when their relationship to score is more ambiguous. As I discussed in my last post about it, not having 'experience' awarded for killing enemies enables a choice about how to approach enemies - whether to engage them or to sneak past; not having a score bonus for killing does the same. The fact that the game doesn't specifically call out skillful moves and reward them is irrelevant; efficiency is its own reward and ends up reflected in the final score. I feel its scoring is close to the optimal resolution for the game - fine enough to measure variations in skill but coarse enough to leave some choices open. So if Zaga-33 ultimately lacks expressivity, I'd say it's despite the scoring, not because of it.

Other roguelikes I've played (mainly Nethack, Rogue, ADOM) have these complex score systems measuring all kinds of things - gold collected, monsters killed, tripe eaten. I tend to ignore them and just pay attention to how far I get; basically I'm modding them to use the same score system as Zaga-33. And I think I'm not the only one, I don't think many players care about these scores unless they're an expert looking for an additional challenge - a "high score" play as an additional optional constraint akin to "ironman", "pacifist", "vegetarian", "atheist".

An advantage of coarse scoring in a game with heavy randomisation is that it covers up some of the variance. If killing enemies is rewarded, someone who draws a powerful weapon will score higher than someone with powerful armour, even if the two items are perfectly balanced in terms of efficiency. That's not an insoluble problem, but it's nice to be able to skip over it entirely.

One other thing - when a game is played repeatedly, we get a sequence of scores. How we interpret that sequence also affects what we count as a good performance. In Zaga-33, how you play differs greatly depending on whether you aim to maximise your maximum score or your average score (although skill at one easily translates to the other, because it entails a good understanding of the underlying system).


So what is it that ultimately determines a game's scope for expression? I think it's quite simple: how many options you have. If there aren't many, there's not much room for different players to make different choices. Comparing Zaga-33 to a similar game like Nethack, its choices are a lot more limited: there are fewer of them altogether, there are fewer alternative options when you make a choice, and they have fewer consequences and interactions. The movement, 4-way versus 8-way, is I think not very significant, but the large number of items, skills, and spells Nethack sports give room for very distinct approaches to situations. Equipment and character progression present decisions with long-term effects.

If there are a large number of options they need to be presented in a way that can be dealt with intuitively. Just selecting from a long list is pretty horrible and overwhelming. Here are some ways I can think of to give lots of alternatives in a reasonable structure:
- Geometrically. Picking from a list of 14 options is hard, but moving a rook on a chessboard is pretty easy to visualise. Picking from a list of infinity options is really hard, but turning and moving in a direction is really easy to visualise.
- Sequentially. A small number of options each turn multiply out to a wider palette of choices - e.g. 4 directions to move in is not many, but after a few turns they give thousands of possible paths.
- Combinatorially. Building a deck of cards, selecting subsets of sets. Race for the Galaxy does this well with the mechanic of spending cards from your hand as payment: you're choosing between dozens or hundreds of alternatives each time, with significant consequences for later moves, but it never feels overwhelming.
- Chronologically. In a real-time game, you constantly make continuous-valued choices about when to act and how long to spend. Tests of speed and reflexes are not so interesting to me on their own, but as a component of a system they can give an extreme variety of possible inputs.


I've been somewhat ambiguous with what I actually mean by "expressivity" here - expressing what exactly? This was intentional: I don't think it particularly matters. A system with room for expressing a particular thing probably has room to express other things too. The default assumption has been "expressing skill at the game", as the posts I'm not-responding to were about, but we could equally much talk about expressing personal character and creativity. In any game that you can spend a lifetime getting better at, skillful play does tend to express a lot about the player's personality. There isn't a single optimal path that everyone is channeled into - if there is, then once it's found the game is essentially solved and therefore not worth spending a lifetime on. There's a close correlation between skill and expression; beginners may make different mistakes but in general they play much more similarly than expert players (although the capacity to recognise the depths of nuance that distinguish experts may be inaccessible to non-experts). In any game played at a tournament level, there are clear differences of personality between professional players in terms of how they approach and play the game.

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