Psychochild's Blog

A developer's musings on game development and writing.

23 January, 2010

Feedback loops in gameplay
Filed under: — Psychochild @ 3:59 AM
(This post has been viewed 9843 times.)

One of the things that new designers should learn is the fearsome power of feedback in gameplay. Great games use feedback to guide the player, letting them master the skills necessary to master the games. With great design comes great power in the form of the feedback loop. For example, a feedback loop can help advance a game; having more units in a strategy game usually allows you to win more battles, leading to the final victory faster.

But, there are also dark sides to the feedback loop when it doesn't start properly or if it becomes self-reinforcing. In this case, the feedback accelerates the loop. The RTS example can turn into a self-reinforcing loop if there is no way to overcome superior numbers in the game through game features like defensive structures. In this case, the player who builds the most powerful side first and plays at least as well as his or her opponent will win.

So, let's take a look at some of the feedback loops in games in more detail.

Feedback is fundamental

All games provide some form of feedback. Graphics or board layouts change, sounds play, items are shifted around, numbers are increased or decreased, etc. Feedback gives the player the information necessary to make decisions on how to play.

Expert designers use feedback to help the player progress. The recent Mario games are usually listed as a prime example how to use feedback to guide the player; give the player a block to hit to get a new ability, and give them a shiny goal to reach using that new ability. Player gets rewarded and learns the basics of a new ability. The player will be expected to master the ability as the game progresses.

Feedback loops come in a lot of other forms as well. In an FPS, the player could be rewarded for more precise aiming at vulnerable locations (HEADSHOT!) In an RPG, the player might be required to gain more levels in order to tackle a higher level enemy. In an RTS, a player who built a stronger economy will most likely be able to build a stronger army (assuming the player who build a small army faster doesn't attack when the economic player is defenseless!) Note that feedback loops happen at different scopes. At a very fine level of detail, a small action such as aiming more precisely in an FPS can help you in a small way. At a larger level of detail, gaining more levels in an RPG can make content easier, even though "gaining levels" requires a lot of individual player actions and decisions.

Feedback loopy

"Feedback loop" is somewhat of a tautology because feedback is always part of a loop. In communication, I say something and you respond to that with your feedback (verbal and non-verbal). In a game, you make a decision and preform a game action, and the game changes based on what you did. Feedback requires interactivity, and games are all about interactivity, which is why feedback is important for a game designer to understand.

The loop part is important to emphasize, however, because it can help a designer think about how feedback works. If the player understands the feedback as it relates to his or her actions, then the game is much more enjoyable. However, if the player does not understand the feedback, this can lead to frustration as an effect seems to have no cause. For example, if the feedback happens a long time after an action is taken (or not taken), this can be really frustrating to the player. A prominent example of this was in some older adventure games, if you did (or did not do) something early in the game it could result in a problem much later in the game, potentially making the game unwinable. If the player has to rely on external sources to avoid such problems, this can diminish the game.

The stalled loop

One problem with a feedback loop is if it has a hard time getting started. For example, if you need a power-up to preform an action but you need to do that action to get a power-up, this can stall a feedback loop. For example in RPG games, if the initial monsters are too hard for a player just starting and thus the player cannot earn experience from defeating monsters, it is hard to gain the levels necessary.

An example of this is found in Lord of the Rings Online's latest addition: Skirmishes. The soldier you get to help you starts off very weak. Tackling content that seems appropriate will actually be much harder because your soldier will not be powerful enough. In order to get more power, you need to earn skirmish marks. To get the marks, you have to succeed in skirmishes. Once you get a powerful enough soldier, collecting the marks becomes easier and completes the feedback loop. However, it can be hard to start the loop in the first place.

The self-reinforcing loop

The opposite of the stalled loop is the self-reinforcing loop. This is when the results of a player action make subsequent actions easier (or sometimes harder) to accomplish. Going back to our RPG example, we might find that getting into a few more random fights increases your level faster and makes it easier and faster to fight other enemies. You advance faster from killing more enemies, giving you a higher level, making it easier to kill, etc. This type of loop is usually called a positive feedback loop.

Sometimes the loop makes things harder. For example, dying in a game where you lose all your possessions can be a negative feedback loop. You might grab a spare set of equipment to go try to reclaim your lost items, but with less powerful equipment the same situation that caused you problems in the first place may be even more difficult to overcome. Eventually you might run out of options and be completely unable to get back to your original level of power without abandoning the situation.

The terms "positive" and "negative" shouldn't be used as a judgment of the desirability of the loop. A positive feedback loop where someone winning will most likely keep on winning can lead to a really frustrating game. Alternatively, a game where a negative feedback loop makes it harder for a winner to keep the lead can lead to more dynamic and interesting game, even if the player in the lead gets frustrated from being dethroned at the wrong time.

Loop with care!

So, what feedback loops have you noticed in games? Which ones do you think are good uses of feedback, and which are poor?

--


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14 Comments »

  1. I find it quite interesting to see the evolution of game feedback over the last two decades. Even in basic feedback loops. Take for example the feedback between a switch that activates a door, which leads to more switches that activate more doors that allow you to progress through a game. Early FPS games used this a fair amount to chunk gameplay (Doom's disappearing walls!) but it was usually a poor quality loop as you had no idea where the door you had just opened was located sometimes. Since then it has evolved with the use of colour-coded switches or keys, improving the feedback again. Even more recently the tendency is to show you a visual of the door that has been activated (Tomb Raider, God of War, etc) or even demonstrate the entire journey you need to take to reach the door.

    There's a subtler side to feedback loops too - they can carry secondary levels of information that becomes important later on. (I guess this would be part of the 'mastering the loop' concept you mention). This can make the game more interesting and challenging. For example, take the notorious 'water dungeons' in Zelda. The initial feedback is that you flip a switch, the water level raises or lowers and you can reach the next section. The subtler feedback is that the switches affect water levels by differing amounts. Sometimes you might need to activate specific combinations to reach specific locations. It's easy to grasp this as the game adds these layers of complexity slowly and without you initially realizing that the change in water level was important.

    Also I would point out a potential "Superstitious Loop" where the player believes an action they have taken has affected the state of something when it was merely a coincidence. This is a common experience in games which have 'action cams' which trigger randomly rather than every time. I recall playing Prince of Persia: Sands of Time, or possibly one of the sequels, and convincing myself that the slow motion 'action cam' was activated based on pressing the right trigger at a specific moment. It turned out that it just happened now and then if the game decided it was cool enough but I spent a good 10 mins trying to trigger it myself!

    Comment by Jpoku — 23 January, 2010 @ 7:35 AM

  2. "Feedback" and "feedback loop" are distinct.

    Feedback is the game's response to your actions that you perceive. A game that gives poor feedback doesn't let you know when you're doing something worth doing or entirely unnecessary. For no particular reason it doesn't let you know the effects of what you are doing in the game world.

    A feedback loop occurs when the feedback alters how you behave so that certain actions become easier or harder that you must do again. Player action -> Feedback -> Repeated player action -> more intense feedback -> etc. This can either be self-reinforcing, as you mentioned, or it can be degenerative. A feedback loop includes feedback and the actions pursued because of that feedback and how this cycle actually continues for some number of cycles--a feedback loop needs to have the capacity to cycle more than once (if not, it isn't a loop because nothing is repeated). Certain feedback itself, though, may never be repeated.

    Feedback loops have a recursive nature. Feedback itself is only a perceptible response.

    Comment by evizaer — 23 January, 2010 @ 12:48 PM

  3. Jpoku wrote:
    a potential "Superstitious Loop"

    Yeah, there are a lot of superstitions in games when some bit of feedback seems to come from a completely unrelated action. However, I think this is mostly caused by the player, not the designer, so it's harder for the designer to control.

    evizaer wrote:
    "Feedback" and "feedback loop" are distinct.

    Yes, but as I pointed out, you can't have feedback without the loop. Taken out of context, the feedback has less meaning in terms of game design. Without the loop, the game becomes passive, like someone watching another person playing. Usually a designer wants to worry about the game giving meaningful feedback to the player based on the loop, and not on making the game look good to spectators who are not (directly) participating in the loop.

    Comment by Psychochild — 23 January, 2010 @ 2:48 PM

  4. /AFK – Let’s All Play Whatever Stargrace Is Playing Edition

    [...] Psychochild. Feedback loops. Psychochild. Feedback loops. Feedback loops. [...]

    Pingback by Bio Break — 24 January, 2010 @ 5:36 AM

  5. The negative feedback loop is something designers really need to worry about, because players will realize it and try and halt the loop to prevent it from occuring. They won't in the way you expect though-they'll try to game it, or use actions that may harm overall game balance.

    The FPS guy may just log out and go to another game before he hits the negative feedback loop to the point where it will cause him to be dethroned. Or he might log out, come back in, and wipe the balancing mechanism out. In a party, if dying causes experience loss and deleveling, players will not step up their game-they will use power leveling and exclude newbies, as well as cherrypick the camps least likely to cause multiple deaths.

    It's dangerous to make too overt a feedback loop, as it will be exploited to deal with it, good or bad.

    Comment by Dblade — 24 January, 2010 @ 2:08 PM

  6. Dungeon bosses in World of Warcraft could do with having a feedback loop of sorts. At the moment they tend to provide a set feedback that warns players, say, of when they're going to enrage or cast an ability. Sometimes, however, although they tell us that they're going to do something, what that something is is obfuscated. It would be nice if this feedback would loop such that repeated attempts generate better, more accurate feedback, so that players would be more inclined to keep try to work out the strategy rather than thinking of their repair bills and the fact that they're unlikely to Guess the Gimmick any time soon, thus going and looking the strategy up on the Internet instead.

    It could be implemented as a skill system, representing the player's character's understanding of the boss; the more they've encountered that boss, the easier it will be for them to understand all of the boss's tricks.

    This sort of enhanced feedback could potentially allow for a more random boss design, which let's a boss select from a pool of gimmicks each fight, rather than the standard and somewhat stale fixed multi-stage design that currently prevails. The higher the character's skill in understanding the boss, the more feedback they will get as to what the next ability will be, and the better the hints as to how to avoid it.

    Comment by Melmoth — 25 January, 2010 @ 9:18 AM

  7. That's not true Dblade. Some games are built on negative feedback loops. Puzzle Fighter is a great example of a negative feedback loop. The more gems on your screen the harder it is to play (a negative loop). At the same time you're also closer to winning because the gems give you extra power to fight back your opponent. Another example would be Mario Kart. The further ahead you are the harder it is to be ahead (you get worse items and get targeted by abilities like blue shell).

    Also not mentioned really in the article: Positive feedback loops are often called slippery slopes and negative feedback loops are often called comeback mechanics. These terms are usually used in reference to what kind of feedback loops dominate the game.

    Comment by Logo — 25 January, 2010 @ 9:42 AM

  8. I'd never thought about feedback loops in game design before but it's (feedback) is something that the web designers at my work keep harping on about. It's a slightly different thing but it seems like the principle idea of making sure people get appropriate and anticipated feedback from completing an action applies to both. "Complete quest and receive item X" is similar in concept to "fill in form and proceed to next step". If the feedback isn't appropriate (or there isn't any) then the user becomes confused, disorientated and ultimately frustrated.

    Comment by We Fly Spitfires — 25 January, 2010 @ 12:01 PM

  9. Psychochild wrote, "Yeah, there are a lot of superstitions in games when some bit of feedback seems to come from a completely unrelated action. However, I think this is mostly caused by the player, not the designer, so it's harder for the designer to control.

    I think the control the designer has involves the timing and quality of feedback given. When the feedback is asynchronous with the events, or the information given in the feedback is sparse or confusing, then it's easy for superstitions to evolve. E.g. if I have a puzzle to solve that involves multiple steps, and the game gives me adequate feedback after each step, then I'm unlikely to form superstitions. If however the game doesn't give me feedback until after I've performed multiple steps, it'll be easy for me to imagine that some meaningless action in the middle of my solving process was in fact essential; thus I'd form a superstition about how to solve the puzzle.

    Psychochild wrote, "Yes, but as I pointed out, you can't have feedback without the loop. Taken out of context, the feedback has less meaning in terms of game design. Without the loop, the game becomes passive, like someone watching another person playing. Usually a designer wants to worry about the game giving meaningful feedback to the player based on the loop, and not on making the game look good to spectators who are not (directly) participating in the loop."

    Evizaer's right; a feedback loop is a recursive structure, which is conceptually distinct from feedback in and of itself. You're right though in that unless the feedback stimulates a change in inputs, the feedback is meaningless. That doesn't necessitate the existence of a feedback loop per se though. "Feedback loop" has a gestalt meaning that's greater than the sum of its parts. It's more than a loop involving feedback; it's a loop that feeds on itself and grows.

    E.g. Say I'm playing a puzzle game. If I guess a problem incorrectly, the game tells me that my answer was wrong (feedback), that will cause me to make another guess. There's a loop of sorts here, from one point of view, but not a feedback loop per se.

    Now say I'm playing an adventure game and trying to defeat a boss monster. My character has a finite amount of health expressed in hearts (a la Zelda), where hearts exist as "containers" that can be filled or empty. The more containers I have, the greater my maximum health. The more filled containers I have, the greater my current health. Death refills all containers, meaning a player can try anew at maximum capacity. Now say that every time a boss monster defeats me, I lose one container, meaning my maximum health is lessened. The game is giving me feedback about my failure by disempowering my character. This can form a negative feedback loop wherein it becomes harder and harder to defeat the boss, and potentially can become impossible.

    Comment by foolsage — 25 January, 2010 @ 2:33 PM

  10. The examples that come to mind are Blizzard games. In Diablo 2 there were quests. You could wander around randomly if you wanted to but it always felt to me like I was being nudged towards a goal from fairly early on. And yet I could very quickly end up in a situation where I was ahead of myself. Clever play could get me to the end boss of the second stage without a lot of random xp grinding but he could be a brick wall until I did spend the time to just randomly kill things and level up. So it always felt like the loop just... dropped you at that point. And it repeated this trend throughout the rest of the game. In World of Warcraft you can grind... but if you wish, you can quest your way from start to max level. You do sacrifice the Big Chain of Events that happens in Diablo 2 as a result of doing the quests but there's at least always something there.

    This part might be a bit off-topic (sorry!) but I think the only improvement I could think of for the WoW quest design is to have more quests that end up being links in a chain story but still provide enough one shots that you don't have to abandon an area if you don't like the current quest chain. Sort of similar to how TV shows have episodes that forward the main plot and others that are mostly filler.

    The LotR online example was amusing. SlothMUD had a similar problem when I played it back in '94. You started in the middle of a city with tons of stuff around you but the only thing you could take on at first were rats scuttling around in the alleyways. All the normal city NPCs were untouchable until much later in the game.

    Comment by Lanir — 25 January, 2010 @ 7:27 PM

  11. Logo:

    Yeah but those feedback loops are tough to balance because you can wind up punishing the player for winning or trying to win. With bad racing games, the rubberbanding can make it so that there is no point to trying to be in first place as opposed to staying in third or so and quickly taking first as the race ends to avoid the AI rubberbanding instantly behind you and overtaking you. Players will soon realize that the best way to win is to game the AI and its loops.

    A puzzle game is tough. Sometimes it isn't a loop at all, they just dump a ton of trash blocks and its game over. If it's a loop, it's one that affects both players. Trash blocks create more trash blocks till someone loses.

    I still think they need to be careful with negative. I think positive developers are pretty good at dealing with, and preventing, but its more common to see negative feedback gone wrong as a player.

    Comment by Dblade — 25 January, 2010 @ 10:53 PM

  12. Foolsage wrote:
    I think the control the designer has involves the timing and quality of feedback given.

    True, but players can form superstitions about anything. One common one I had when I was younger was pounding a button on a console RPG like Dragon Warrior. I had a superstition that pushing the button in a certain way seemed to give me better combat results. That's probably not the case, though; all that did was help me get through the battle menus faster if I didn't do anything out of the ordinary. Except for laying the mechanics of the game bare (which has its own design challenges), I don't think there's anyway to prevent people from forming some superstitions like that.

    It's more than a loop involving feedback; it's a loop that feeds on itself and grows.

    I guess it's a question of how you define it. To me, feedback outside of the loop is without context -- it becomes simply information. Without knowing the context, the feedback is less meaningful. A feedback loop doesn't have to require iteration, it's part of the loop where the player makes a decision and the game gives information (feedback).

    You and evizaer are right in that the game design implications get a lot more interesting when you repeat the loop over time. The quality of the feedback is also important, as you point out. Finally, designers need to make sure the feedback accomplishes the game design goals. This is the main thing I wanted to touch on in this post.

    Thanks for the, er... feedback? ;)

    Comment by Psychochild — 26 January, 2010 @ 2:49 AM

  13. "Thanks for the, er... feedback? ;)"

    Oh dear :D

    Comment by We Fly Spitfires — 26 January, 2010 @ 3:31 AM

  14. A couple of extra notes....

    It’s important to bear in mind what Brian said about the terms “positive” and “negative”: in the context of self-regulating systems (i.e., feedback loops), those terms don’t mean “good” or “bad.” Positive just means that the inputs to the system are reinforced, while negative only means that the inputs are reduced -- there’s no judgment made about the inherent value of either approach.

    This understanding -- reinforcement versus reduction -- leads to anther point, which is that the really dangerous kind of feedback loop is the positive feedback loop. Negative feedback into a loop is generally safe. Because it reduces inputs, it’s self-limiting: eventually the feedback equals the input and you have a steady-state condition. A classic physical example of this is the “governor” [http://en.wikipedia.org/wiki/Centrifugal_governor ].

    In general, a negative feedback system is useful when your design goal is to achieve a steady state of some behavior. Make an action worth doing, but apply some kind of limited negative feedback to that action, and the system will self-regulate -- people will do it, but only up to a point. (Judging how much negative feedback to supply is part of the art of design.)

    Positive feedback systems are the dangerous ones because they amplify inputs. You get more of whatever you started with, which can lead a system into “too much of a good thing” territory. Addictive behavior is usually a sign that a positive feedback loop is operating. (Read Michael Crichton’s novel “The Terminal Man” for a human-centric example of this principle.) In game design terms, positive feedback loops can be seen as rewarding players for doing something they already had a reason to want to do. They already want to do it; rewarding them for doing just makes them want to keep doing it to the exclusion of everything else.

    Farming low-level mobs for both loot and XP is a very general example of this effect. Receiving either would be nice; getting both just encourages more of that behavior until boredom -- a kind of negative feedback -- grows large enough to offset the perceived value of the rewards for repeating the loop.

    Finally, consider that “playing a MMO” is itself a kind of loop -- maybe you want to think about providing some form of negative feedback so that your players don’t get *too* obsessed....

    Comment by Bart Stewart — 18 February, 2010 @ 2:33 PM

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