Varieties of “game” bugs

In the first article, we talked about the types of testing used in games, and now let’s talk about the result that confuses PMs, introduces developers into the paint and is so extremely intolerant of Product Owners in production – bugs. Today I also classify them and show you some of them with examples.

I think a lot of people have seen this bug from Assassins Creed.  The reasons may be different - the mesh was not loaded or the material or material is completely wrong.  And also do not exclude the possibility of enabling LOD mesh, which is not installed in
I think a lot of people have seen this bug from Assassins Creed. The reasons may be different – the mesh was not loaded or the material or material is completely wrong. And also do not exclude the possibility of enabling LOD mesh, which is not installed in

It would be strange if there were no bugs in such a complex system as video games. They are, they are common, and this bestiary is extremely diverse here. Having familiarized yourself with the above types of testing for games, I think you can guess that bugs in video games are not only encountered “404 not found” and “game crashed”. Let’s go over the most common ones in the gaming industry!

To category Visual bugs will include: any visible artifacts (Visible Artefacts), missing textures (missing textures), Clipping, Screen tearing, Z-fighting

Examples of visual bugs can be found below:

Visual Artefacts – any visual bugs that do not fall under other types.

Whoops ... Something Went Wrong
Whoops … Something Went Wrong

Missing Textures – missing / missing textures. Usually, in their place, they try to put a “stub” in the form of a bright default texture in the form of a checkerboard. This is not necessary, but thanks to this approach, missing textures are visible to the naked eye.

Missing texture and good example "chess" instead of the lost file
Missing texture and good example of “checkerboard” instead of a lost file

Z-fighting – this bug appears when several primitives are located at approximately the same distance to the camera and they have virtually the same values ​​in the Z-buffer that track the depth. Because of this, primitives can be partially displayed one above the other.

Screen tearing or “screen tearing” is a visual artifact that displays information from multiple frames in a single image.

Culling and Clipping – bugs related to the rendering and graphics pipeline. Often – the intersection of two objects, in which one obscures the geometry of the other, hiding it from view. If you go a little deeper, then Culling – this is cutting off what is obviously invisible. In this case, the game will not even try to draw this segment. Culling is different, and here are some examples: rustrum culling – clipping by pyramid of visibility, backface culling – cutting off the “back” edges, occlusion culling – clipping of faces to the fact of their overlap by other geometry, depth culling – overlapping one geometry with another that has already been drawn, but based on the depth buffer. But when a sufficiently large polygon is drawn and everything that is known to be outside the screen is cut off from it, this is already Clipping
It is also worth highlighting a similar, but essentially different bug – collision problems. In video games, clipping can be associated with a set of algorithms that respond to the interaction of two adjacent or overlapping geometries (collision detection). And to identify such bugs, there are special viewing modes (view modes), but I’ll talk about this in the next article.

This is how you can easily "to come in" into an object with a collision curve (or without it at all)
This is how you can easily “enter” an object with a collision curve (or without it at all)
A bug of this kind can also be described with the term occlusion, i.e.  overlapping of one object with another is not how it was intended.
A bug of this kind can also be described with the term occlusion, i.e. overlapping of one object with another is not how it was intended.

Within the framework of Audio bugs groups, I will highlight quite basic, but no less annoying things: not being able to play SFX / music / dialogue, pass (trigger) losing, poor mixing (sound is too low or loud), distortion (distortions), drops

Level design bugs – invisible walls (invisible walls), gaps in the map (map holes), jams (stuck spots) etc. Also, bugs related to the Navigation Mesh are among the bugs of the level design. Below are some examples of level design bugs:

Invisible Walls (invisible walls) can be both a bug and a feature. Previously, they limited the movement of the player’s character and did not allow them to go further than necessary. Now they are trying not to create “invisible obstacles”, but to limit the “passability” with the help of level design, for example, set up an impassable obstacle, barricade, mountains, city gates, etc. Showing the player that there is something ahead, but at the same time using invisible walls to prevent the character from entering this area – signs of poor level design. Nowadays, they almost do not do this, and invisible walls can often be the result of level reconstruction: for example, some model could be forgotten to be removed or an invisible element was added as a temporary stub.

The hero cannot go further because of the invisible wall, but the road still does not end ...
The hero cannot go further because of the invisible wall, but the road still does not end …

Map holes most often caused by not tight fit of the planes of objects (floor, walls, etc.). These are places where the user can, unplanned for the developers, get outside the game zone. Such bugs are often called Out of Bounds.

And this is how your game looks like "from within"
And this is how your game looks “from the inside”

Bugs Navigation Mesh often involve level rebuilding or automatic mesh generation. For example, you have moved items, but the nav grid remains the same. As a result, your NPCs can “walk into the wall” or any other object that they cannot bypass and will stick there (one of the cases Stuck points).

Here the Nav Mesh goes through the objects in the red circle.
Here the Nav Mesh goes through the objects in the red circle.

Artificial Intelligence Errors (AI): NPCs don’t move, stuck, don’t follow the player, intended interaction with objects does not work, getting stuck, NPCs do things that were not originally intended, etc.

Since we also have a part of the engine responsible for physics, it would be strange if there were no bugs with physics. It can be almost anything: levitating objects, unrealistic physics, acceleration over normal, as well as the blasting of objects “into space” due to the addition of vectors when processing contacts. Bugs of this kind you could see in memes of various games, for example GTA 5 or, from the actual point, Cyberpunk 2077. A good analysis of many bugs from Cyberpunk 2077, including the ones just described. can be seen here

Roach, what are you doing ???
Roach, what are you doing ???
Flying cars are not uncommon in Cyberpunk 2077
Flying cars are not uncommon in Cyberpunk 2077

Stability and performance bugs include friezes, crashes, black screens, inability to load a level, loading of high poly models visible to the user, or any objects in general, FPS drawdown, oooooooooo long loading, as well as microfreezes (loading). To this I will add too long installation of the game, as well as the inability to run the game on a PC with the minimum permissible requirements.

Sorry, I didn’t recognize you ... Your face didn’t sink
Sorry, I didn’t recognize you … Your face didn’t sink

Are not rare and compatibility bugs… Particularly common examples are as follows: on some video cards may meet crash (for example, on the minimum possible requirements or new video cards on the market), controllers of a particular company does not work, the game does not start on some specific version OS, wireless headset outputs sound in mono, etc.

About problems online all have heard of games. Bad connection, lags, “invisible players“or” I went around the corner and they killed me “, scoring errors, impossibility of reconnect (if there is such a feature), loss of packets during the game, discrepancy in the calculations of information between the client, de-identified by the server and the back-end. Also, if the connection is poor, some interface elements can be used several times, something may not load and “disappear”, etc., but, as a rule, these are UI bugs and do not greatly affect the player’s user experience.

With the same number of repetitions, the campaign is no longer a bug, but a feature.  Time to introduce Diablo 2 queues
With the same number of repetitions, the campaign is no longer a bug, but a feature. Time to introduce Diablo 2 queues

Under bugs localization and compliance, from non-trivial, can be attributed localization of advertising, the placement of different materials in the same places in different regions and countries (for example, in this country it is forbidden to show one, and in another it is not prohibited, or the age qualification under which the game falls may not allow anything to be shown in this or that region). Date manipulation on your device and the failure of the client with the server, I would also refer here. Well, no one has canceled the “classic” localization and internationalization bugs. You can learn more about them and about approaches to their correct and complete testing. read in my article

Why do I need text?  And it's also clear where to click!
Why do I need text? And it’s also clear where to click!
And people, and kioni, and everything-everything is mixed here
And people, and kioni, and everything-everything is mixed here

Is this really all?

Of course not. These are not all types of game bugs, but perhaps the most frequently encountered. I have not touched on here mismatch bugs, such as “the element is written to blueprints one by one, to the back-end – in another way, the object or its attributes (ID, description, etc.) forgot to add somewhere, etc. this is no longer about the specifics of games, but in general, malfunctions that can be in many programs.

What bugs have you encountered while playing or working on the game? I would be glad to chat with you on this and other relevant topics in the comments!

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