Unity 2D: Building UI System for Monster Chase game

Create a new scene for UI system of Monster Game.

/*
* Go to File » New Scene » Basic 2D (Built-in) » Create (button)
* Hierarchy » Untitled » three dot menu » Save scene » Scenes (choose directory) » MainMenu (named) » Save (button)
*/

Create a new UI image by right-click on empty space of hierarchy, then select "Image" from UI menu and renamed it with "BG".
When creating a UI element for the first time in a project scene, Canvas & EventSystem object will be automatically created by default.

Because every UI element must be wrapped by a Canvas object and any event on the UI element must be tracked by an EventSystem object.

/*
* Inspector (Canvas GameObject)
* Canvas » Render Mode » Screen Space - Camera (select)
* Canvas » Render Mode » Render Camera » Main Camera (drag from hierarchy)
* Canvas Scaler » UI Scale Mode » Scale With Screen Size (select)
* Canvas Scaler » Reference Resolution : x = 1920, y = 1080
* Canvas Scaler » Match » 0.5
*/

Add the background sprite image to the BG UI and adjust the position of background on the scene.

/*
* Inspector (BG GameObject)
* Image » Source Image » Background (drag from Sprites folder)
* Rect Transform » Anchor » Stretch center » Scale the image (using Rect Tool)
* Rect Transform » Left: 0, Top: 0, Pos Z: 0, Right: 0, Bottom: 0
*/

Create a new UI image object called "Moon" under the Canvas obj and add moon sprite image on it.

/*
* Inspector (Moon GameObject)
* Image » Source Image » Moon (drag from Sprites folder)
* Image » Set Native Size (button) (click)
* Rect Transform » Anchor » top left
* Rect Transform » Pos X: 208 (any), Pos Y: -189 (any), Pos Z: 0
* Rect Transform » Width: 493, Height: 446
*/

Create a new UI text object called "Game Logo" under the Canvas obj and add text on it.

/*
* Inspector (Game Logo GameObject)
* Rect Transform » Pos X: 73 (any), Pos Y: 307 (any),Pos Z: 0
* Rect Transform » Width: 1511 (any), Height: 433 (any)
* Text » Text » Monster Chase (enter)
* Text » Character » Font » FEASFBI_ (drag from Fonts folder)
* Text » Character » Font Style » Bold
* Text » Character » Font Size » 230
* Text » Paragraph » Alignment » Horizontal : Center, Vertical : Center  
* Text » Color » White (#fff)
*/

Select the Player Select.png asset from the sprites assets directory.

/*
* Inspector (Player Select.png Sprite Asset)
* Sprite Mode » Multiple (change) » Apply (button)
* Sprite Editor » Fullscreen (maximize) 
* Sprite Editor » Slice » Type » Automatic (select) » Slice (button)
* Sprite Editor » Player Select_0 (slice outlined) » Player 1 Select (rename)
* Sprite Editor » Player Select_1 (slice outlined) » Player 2 Select (rename)
* Sprite Editor » Apply (button)
*/

Create a new object on the hierarchy called "Main Menu Controller" and reset it transform.

/*
* Inspector (Main Menu Controller GameObject)
* Transform » Reset
* Add Component » New Script » MainMenuController (named)» Create and Add
*/

Create two new UI button object called "0" & "1" under the Canvas obj and add player select sprite image on it.

/*
* Inspector (0 & 1 GameObject)
* First delete text object of button from the hierarchy
* 0 (obj) » Rect Transform » Pos X: -326 (any), Pos Y: -150 (any), Pos Z: 0
* 1 (obj) » Rect Transform » Pos X: 326 (any), Pos Y: -150 (any), Pos Z: 0
* Rect Transform » Width: 341 (any), Height: 341 (any)
* 0 (obj) » Image » Source Image » Player 1 Select (drag from Sprites folder)
* 1 (obj) » Image » Source Image » Player 2 Select (drag from Sprites folder)
* On Click () » Add empty event » Main Menu Controller (drag from hierarchy) » PlayGame (select method from MainMenuController script)
*/

To compile all the scene for the build, you must add the scenes on the build settings.
```
// File » Build Settings... » Scenes In Build » Add Open Scenes (button)
```

Create an "Game Manager" empty game object on hierarchy with transform reset.

/*
* Inspector (Game Manager GameObject)
* Transform » Reset
* Add Component » New Script » GameManager (named) » Create and Add
* Game Manager (Script) » Characters (property) » Player 1 & Player 2 (drag from prefabs)
*/