Tutorial on how to create a first-person shooter (FPS) game in Scratch.

• Create a new Scratch project and delete the default sprite.

• Add a backdrop for the game.

• Add a score label to display the score.

• Create a new sprite for the player.

• Create a script for the player to move around the screen using the arrow keys.

• Use the "if then" block to detect when the player sprite hits the edge of the screen. When the player sprite hits the edge of the screen, bounce it back in the opposite direction.

• Add new sprites for the enemies.

• Create scripts for the enemies to move around the screen randomly.

• Use the "if then" block to detect when the enemy sprite hits the player sprite. When the enemy sprite hits the player sprite, decrease the score by one point and move the player sprite back to the center of the screen.

• Add a new sprite for the bullet.

• Create a script for the player to shoot bullets using the space bar.

• Use the "if then" block to detect when the bullet hits an enemy sprite. When the bullet hits an enemy sprite, remove both the bullet and the enemy sprite from the screen.

• Create a variable to store the player's score.

• Display the score on the screen using a label.

• Use the "change score by" block to increase the score when the player shoots an enemy sprite.

• When the game is over, display a "Game Over" message and pause the game.

• Add a "Restart Game" button to the screen that clears the screen, resets the score to zero, and allows the player to start a new game.

• Test the game thoroughly to ensure that the player moves smoothly, the enemies are detected correctly, and the shooting system works as intended.

• Refine the game as needed by adjusting the enemy speed, bullet speed, and scoring system.

By following these steps, you can create a simple FPS game in Scratch. However, keep in mind that Scratch is a block-based visual programming language, and creating a complex FPS game with advanced graphics and features may not be possible. Nonetheless, you can still create a fun and engaging game that showcases your creativity and programming skills. 

Don't forget to share your creation with the Scratch community and seek feedback from other users to improve your game further. And install the Scratch Master app for more such detailed tutorials.