Access level modifiers should be explicitly defined for classes, methods and member variables. This includes defining private even though C# will implicitly add it.

Use the least accessible access modifier, except for public member that is expected to be used by other classes in the future.

Fields & Variables

Prefer single declaration per line.

BAD:

string username, twitterHandle;

GOOD:

string username;
string twitterHandle;

Spacing is especially important to make code more readable.

Indentation

Indentation should be done using tabs — never spaces .

Blocks

Indentation for blocks uses tabs for optimal readability:

BAD:

for (int i = 0; i < 10; i++) 
{
  Debug.Log("index=" + i);
}

GOOD:

for (int i = 0; i < 10; i++) 
{
    Debug.Log("index=" + i);
}

Line Wraps

Indentation tab for line wraps should use 4 spaces (not the default 8):

BAD:

CoolUiWidget widget =
        someIncrediblyLongExpression(that, reallyWouldNotFit, on, aSingle, line);

GOOD:

CoolUiWidget widget =
    someIncrediblyLongExpression(that, reallyWouldNotFit, on, aSingle, line);

Line Length

Lines should be no longer than 100 characters long.

Vertical Spacing

There should be just one or two blank lines between methods to aid in visual clarity and organization. Whitespace within methods should separate functionality, but having too many sections in a method often means you should refactor into several methods.

All braces get their own line as it is a C# convention:

BAD:

class MyClass {
    void DoSomething() {
        if (someTest) {
          // ...
        } else {
          // ...
        }
    }
}

GOOD:

class MyClass
{
    void DoSomething()
    {
        if (someTest)
        {
          // ...
        }
        else
        {
          // ...
        }
    }
}

Conditional statements are preferred to be enclosed with braces, irrespective of the number of lines required. Some cases can be pardoned.

BAD:

if (someTest)
    doSomething();  

if (someTest) doSomethingElse();

GOOD:

if (someTest) 
{
    DoSomething();
}  

if (someTest)
{
    DoSomethingElse();
}

Exactly one class, struct, enum, or interface per source file, although inner classes are encouraged where scoping appropriate.

Switch-statements come with default case by default (heh). If the default case is never reached, be sure to remove it.

If the default case is an unexpected value, it is encouraged to log and return an error

BAD

switch (variable) 
{
    case 1:
        break;
    case 2:
        break;
    default:
        break;
}

GOOD

switch (variable) 
{
    case 1:
        break;
    case 2:
        break;
}

BETTER

switch (variable) 
{
    case 1:
        break;
    case 2:
        break;
    default:
        Debug.LogError("Unexpected value when...");
        return;
}

Use US English spelling.

BAD:

string colour = "red";

GOOD:

string color = "red";

The exception here is MonoBehaviour as that's what the class is actually called.

Whenever someone add a script implementing NetworkBehaviour, they have access to the following attributes, indicating if a given method should be server only, client only, or both :

• [Server] for server only code.

• [Client] for client only code.

• [ServerOrClient] for both.

Make sure no methods goes without an attribute in a script inheriting NetworkBehaviour. The goal is to increase readability and to generate warnings or exceptions when clients or server are attempting to call something they should not.

Methods with [ServerOrClient] attributes should stay uncommon, they make debugging harder. If possible, try to refactor the code to avoid them.

This section includes some rules of thumb for design patterns and code structure

Error handling

Avoid throwing exceptions. Instead log and error. Methods returning values should return null in addition to logging an error

BAD:

public List<Transform> FindAThing(int arg){
    ...
    if (notFound) {
        throw new NotFoundException();
    }
}

GOOD:

public List<Transform> FindAThing(int arg){
    ...
    if (notFound) {
        Debug.LogError("Thing not found");
        return null;
    }
}

Finding references

Don't use Find or in other ways refer to GameObjects by name or child index when possible. Reference by reference is less error prone and more flexible. Expect people to set the fields in the inspector and log warnings if they don't.

BAD:

private GameObject _someMember;

private void Start() {
    _someMember = GameObject.Find("ObjectName");
}

RequireComponent

Prefer RequireComponent and GetComponent over AddComponent. Having the components in the inspector let's us edit them. AddComponent limits us.

BAD:

public class : MonoBehaviour
{
    private AudioSource _audioSource;

    private void Start() {
        _audioSource = gameObject.AddCompenent<AudioSource>();
    }
}

GOOD:

[RequireComponent(typeof(AudioSource))]
public class : MonoBehaviour
{
    private AudioSource _audioSource;

    private void Start() {
        _audioSource = GetCompenent<AudioSource>();
    }
}

Properties with backing fields

Properties can be used for access control to fields, and when using backing fields they can be private and let us change them in the inspector. Consider when a fields should be public and prefer properties with backing fields.

Sometimes it's just nice to see them for debugging, even if we don't change them, so consider making more of your private fields visible.

OKAY:

public GameObject SomeMember;

BETTER:

[SerializeField] private GameObject _someMember;
public GameObject SomeMember => _someMember;

A class must respect the following order, from top to bottom

• Events and delegates declaration.

• Private enums declaration.

• Private internal classes.

• Member variables.

• Properties.

• Methods.

BAD:

 public sealed class Container : NetworkActor
    {
        public event ContainerContentsHandler OnContentsChanged;

        public Vector2Int Size;
        public AttachedContainer AttachedTo { get; set; }
        
        [SyncObject]
        private readonly SyncList<StoredItem> _storedItems = new();
        
        private readonly object _modificationLock = new();
        
        public float LastModification { get; private set; }
        
        public delegate void ContainerContentsHandler(Container container, IEnumerable<Item> oldItems,IEnumerable<Item> newItems, ContainerChangeType type);

        ...

GOOD:

 public sealed class Container : NetworkActor
    {
        public event ContainerContentsHandler OnContentsChanged;
        public delegate void ContainerContentsHandler(Container container, IEnumerable<Item> oldItems,IEnumerable<Item> newItems, ContainerChangeType type);
  
        public Vector2Int Size; 
        private readonly object _modificationLock = new();
        
        [SyncObject]
        private readonly SyncList<StoredItem> _storedItems = new();
        
        public AttachedContainer AttachedTo { get; set; }
        public float LastModification { get; private set; }
   

        ...