A simple dungeon creation script for C# (with visualization in Unity)

RecursiveDungeon.cs

// 1. Create UI -> Image
// 2. Add this script to Image
// 3. Press Space in Game Mode

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;

public class RecursiveDungeon : MonoBehaviour
{
    [SerializeField] Image image;
    [SerializeField] int mapSizeHorizontal = 121;
    [SerializeField] int mapSizeVertical = 81;
    [SerializeField] int roomMinHorizontal = 11;
    [SerializeField] int roomMinVertical = 9;
    [SerializeField] int extraDoorChance = 15;
    [SerializeField] int minLengthForExtraDoor = 40;
    [SerializeField] int mapScale = 2;
    int[,] maze;

    void Awake()
    {
        image = GetComponent<Image>();
    }

    void Update()
    {
        if (Input.GetKeyDown(KeyCode.Space)) CreateDungeon();
    }

    void CreateDungeon()
    {
        if (mapSizeHorizontal % 2 == 0) mapSizeHorizontal++; // Odd numbers only.
        if (mapSizeVertical % 2 == 0) mapSizeVertical++; // Odd numbers only.
        maze = new int[mapSizeHorizontal, mapSizeVertical];
        Division(1, mapSizeHorizontal - 2, 1, mapSizeVertical - 2);

        image.rectTransform.SetSizeWithCurrentAnchors(RectTransform.Axis.Horizontal, mapSizeHorizontal * mapScale);
        image.rectTransform.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, mapSizeVertical * mapScale);
        Texture2D texture = new Texture2D(mapSizeHorizontal, mapSizeVertical);
        Sprite sprite = Sprite.Create(texture, new Rect(0, 0, mapSizeHorizontal, mapSizeVertical), Vector2.zero);
        sprite.texture.filterMode = FilterMode.Point;
        image.sprite = sprite;
        for (int x = 0; x < mapSizeHorizontal; x++)
        {
            for (int y = 0; y < mapSizeVertical; y++)
            {
                if (x == 0 || y == 0 || x == mapSizeHorizontal - 1 || y == mapSizeVertical - 1) maze[x, y] = 1;
                Color pixelColour = Color.black;
                if (maze[x, y] == 1) pixelColour = Color.white; // wall
                else if (maze[x, y] == 2) pixelColour = Color.black; // door
                texture.SetPixel(x, y, pixelColour);
            }
        }
        texture.Apply();
    }

    void Division(int startX, int endX, int startY, int endY)
    {
        if (endX - startX + 1 < roomMinHorizontal * 2 && endY - startY + 1 < roomMinVertical * 2) return;

        if (endX - startX > endY - startY)
        {
            if (endX - startX + 1 < roomMinHorizontal * 2) return;
            CreateRoom(true, startX, endX, startY, endY);
        }
        else if (endX - startX < endY - startY)
        {
            if (endY - startY + 1 < roomMinVertical * 2) return;
            CreateRoom(false, startX, endX, startY, endY);
        }
        else
        {
            if (Random.value > 0.5f)
            {
                if (endX - startX + 1 < roomMinHorizontal * 2) return;
                CreateRoom(true, startX, endX, startY, endY);
            }
            else
            {
                if (endY - startY + 1 < roomMinVertical * 2) return;
                CreateRoom(false, startX, endX, startY, endY);
            }
        }
    }

    void CreateRoom(bool isHorizontal, int startX, int endX, int startY, int endY)
    {
        if (isHorizontal)
        {
            int verticalWall = Random.Range((startX + roomMinHorizontal), endX + 1 - roomMinHorizontal);
            if (verticalWall % 2 == 0) // Odd numbers only.
            {
                verticalWall++;
                if (verticalWall >= (endX + 1 - roomMinHorizontal)) verticalWall -= 2;
            }
            for (int i = startY; i <= endY; i++)
            {
                maze[verticalWall, i] = 1;
            }
            int doorNumbers = 1;
            if (extraDoorChance > Random.Range(0, 100) && endY - startY >= minLengthForExtraDoor) doorNumbers++;
            for (int i = 0; i < doorNumbers; i++)
            {
                int randomDoor = Random.Range(startY, endY + 1);
                if (randomDoor % 2 != 0)
                {
                    randomDoor++;
                    if (randomDoor > endY) randomDoor -= 2;
                }
                maze[verticalWall, randomDoor] = 2;
            }
            Division(startX, verticalWall - 1, startY, endY);
            Division(verticalWall + 1, endX, startY, endY);
        }
        else
        {
            int horizontalWall = Random.Range(startY + roomMinVertical, endY + 1 - roomMinVertical);
            if (horizontalWall % 2 == 0) // Odd numbers only.
            {
                horizontalWall++;
                if (horizontalWall >= endY + 1 - roomMinVertical) horizontalWall -= 2;
            }
            for (int i = startX; i <= endX; i++)
            {
                maze[i, horizontalWall] = 1;
            }
            int doorNumbers = 1;
            if (extraDoorChance > Random.Range(0, 100) && endX - startX >= minLengthForExtraDoor) doorNumbers++;
            for (int i = 0; i < doorNumbers; i++)
            {
                int randomDoor = Random.Range(startX, endX + 1);
                if (randomDoor % 2 != 0)
                {
                    randomDoor++;
                    if (randomDoor > endX) randomDoor -= 2;
                }
                maze[randomDoor, horizontalWall] = 2;
            }
            Division(startX, endX, startY, horizontalWall - 1);
            Division(startX, endX, horizontalWall + 1, endY);
        }
    }
}