Featured Blog

Design Rant: In-game logic

A short rant on consistency in world rules and immersion and some tips on consistency.
Or why being consistent is so damned important

There is an obvious difference between real-world logic and in-game logic. We know that in the real world, you don’t heal from bullet wounds just by picking up a first-aid kit, or just by sitting behind some cover for nearly half a minute. We know that you can’t run for hours on end with fifteen different weapons strapped to your person and we sure as hell can't cut hair longer. Yet we accept these things in games –even ‘realistic’ ones- because when you’re playing a game, different rules about what makes sense and what doesn't apply. It’s part of the entire fun of games.

Hurting the suspension of disbelief by being inconsistent


Accepting something of which we know it cannot be true because you know on some level that it is all make-belief is called  ‘suspension of disbelief’. It is a little trick our minds pull on us, and it is what allows us to enjoy movies and games. Prerequisite for the functioning the suspension of disbelief though, is that if the fiction establishes rules, or implies rules, it abides by these self-imposed rules. Meaning that if the game applies damage to the game character when the player makes a jump down a four-meter ledge, this should apply throughout the entire game -even cut scenes- unless a logical explanation is offered (e.g. the surface is softer, there is less gravity). For example, in Halo 2 there is a rule where players are killed if they jump down from ledges too high. The trigger functions either by using location (if a player is here, he must be falling, so he will die) or by the player’s speed (if the player is going this fast, he must be falling, so he will die). What has always bugged me is that there are several segments in the cut-scenes in halo 2 where Master Chief jumps down to a spot you as a player could not go, because the trigger would kill you. In the cut-scene though, this action is suddenly allowed. By being inconsistent with the in-game rules we apply, we’re hurting the player’s suspension of disbelief. Every time a player has a thought which comes close to ‘huh, why is this suddenly allowed now?!’ he is thinking about the game’s design, and that takes him away from immersion.

Frustrating the player by being creative with the rules


Another thing is, even though we don’t expect games to follow real-world rules to the letter, we do expect them to have at least some semblance of these real-world laws to them. Maybe a game-character can jump really high, but at least he'll come down eventually. Or maybe a character can take a lot more bullet hits than any real person, but at least he will die if he gets hit often enough. Not abiding by these real-world laws at all is just fine in some cases, as long as you make sure that there are another set of laws in place which are just as strict and consistent. Beware that forgoing real world rules at all might make it harder for your players to find something relatable in your game-world. In certain instances not applying at least some real world logic to games can make it feel really unfair to players. Especially when these inconsistencies are being used to ramp up difficulty in the game in general or in certain segments.

Enemy AI logic


It struck me while I was playing Bioshock: infinite; I was playing the segment where you have to defend an airship against enemy Zeppelins; The zeppelins drop units called ‘Patriots’ in endless succession until you destroy the zeppelin. The part where it started feeling unfair is, that the Patriots are dropped in pairs of two, and whenever you destroy them, a new pair is immediately dropped down to replace them. Why would your enemies do this? Certainly they can just drop more Patriots, they seem to have an infinite number of them. Why wait until the first pair is destroyed before dropping another? This is an argument which assumes a real-world logic to the actions of the AI enemies.

Obviously players are usually aware that enemy AI’s aren’t governed by real-world logic, but it is segments like these where you really shove it in their faces which breaks immersion. What is worse is that this way feels really unfair to players, they take out the Patriots to buy time to focus on attacking the Zeppelins, if the Patriots are just continuous, there’s just no merit to killing them. The entire segment starts feeling unfair. Again it makes perfect sense for game designers to do this, as it’s  convenient to have a pair of Patriots being destroyed function as a trigger to launch the next pair. It ensures that the same level of challenge is maintained, for there is always at least one Patriot to battle. Perceptive players however will catch on to this, if not consciously then at the very least subconsciously in a persistent feeling of unfairness. And because players start thinking about ‘why would the enemy do this, it makes no sense not even in the in-game world’, players lose the feeling of immersion as well. They end up feeling treated unfairly and frustrated.

Unfair advantages


Another good example is in Far Cry 3. In that game, if a player fires a shot with a silenced weapon and kills the target, none of the other enemies are alerted unless they see it directly. Not even when it happens right behind them. The audible *thump* of a body falling on the floor is obviously not something they register. But if the player is inaccurate and misses even a single shot, even from hundreds of metres and even with a silenced weapon, each and every enemy in the vicinity will know exactly where he is and face his direction immediately. Based, apparently, on the sound of bullet hitting something. Suddenly, those deaf guards who couldn't even hear their buddy fall right behind them, have super-hearing. Fair? Not much.

Convenient for designers though, as the player is punished for having missed the shot, and the sneaking phase is now transferred to the combat phase. The same feeling of unfairness we spoke of before is triggered in players though. In-game logic dictates that enemies can’t hear a silenced shot being fired, even when the impact is fairly close to them. But suddenly this in-game world rule is being broken when the player misses the shot. Examples like these are the result of another problem: Designers often use lazy design choices to ramp up the difficulty in their games. This is a different subject which I will discuss in a later post. Thus far we have two main problems with being inconsistent with your in-game logic; it breaks the suspension of disbelief, and thereby immersion and it feels unfair to players.

There is a third problem as well, regularly being inconsistent with in-game rules makes your game world feel really loose-weave. None of this implies that you should never change up the rules in your game-world, in fact, changing up the rules from time to time can ensure the interaction stays fresh for the player. The ever-important key in all this is –as usual- communication. If you make sure that you communicate the changes, and why these changes occur, to your players, it will offer an in-game explanation for the change (reducing loss of immersion) and an explanation from a play standpoint (reducing feelings of unfairness).

How to keep your in-game rules consistent


The big problem with keeping your rules consistent is finding out if and where your rules conflict with one-another. Diligent playtesting with the specific goal of finding these inconsistencies should help you find out where they are. During playtests, a few tell-tale signs of your game rules being inconsistent are if players complain about losing immersion, if they mention the game's design during play or if they indicate they feel they are being treated unfairly.

Don't confuse players indicating an unfair treatment with them complaining about difficulty, these are two very different things. An easy way to make sure you keep your rules consistent is to make sure you communicate them clearly across your development team. Don’t just keep them in the design document –nobody reads those anyway- but print them out and hang them in the office. Make sure that people who are responsible for creating the cut-scenes are as familiar with the rules as the game’s designers are.

This is another instance where it helps to have in-game rules which are tied in with real-world rules; the more relatable the in-game rules are, the easier it is to keep track of them. Don’t just assume that as soon as the rules are programmed into the engine, the engine will take care of it for you.   Play through your own game with ‘designer-vision’, purposefully scanning for instances where rules or systems might be conflicting with one-another. Be wary of employing lazy design solutions when confronted with having to ramp up the difficulty in your games. For me personally it usually helps to graphically map out rules which could influence one another to be able to catch inconsistencies early on. Whenever your encounter a player mentioning that he felt unfairly treated by the game, maybe he really isn't just a sore loser, it could just be that you failed to keep your in-game rules consistent.

Have you ever encountered a situation where it really felt like the computer-controlled opponents were really thinking? No, but I've rarely encountered games where it feels like my human opponents are really thinking, either.” - Flynt,

Have you encountered examples of games being really inconsistent in their rules recently? Leave a comment below!

Latest Jobs


Hybrid, Cambridge, MA or Chicago, IL
Quality Assurance Lead

Bladework games

Remote (United States)
Senior Gameplay Engineer

High Fidelity, Inc.

Game Interaction Designer

Fred Rogers Productions

Hybrid (424 South 27th Street, Pittsburgh, PA, USA
Producer - Games & Websites
More Jobs   


Explore the
Advertise with
Follow us

Game Developer Job Board

Game Developer


Explore the

Game Developer Job Board

Browse open positions across the game industry or recruit new talent for your studio

Advertise with

Game Developer

Engage game professionals and drive sales using an array of Game Developer media solutions to meet your objectives.

Learn More
Follow us


Follow us @gamedevdotcom to stay up-to-date with the latest news & insider information about events & more