**Building Tetris HTML**

I'm focusing on integrating all the necessary HTML, CSS, and JavaScript for a self-contained Tetris game within a single `index.html` file. The canvas element is my primary rendering surface.

**Structuring Tetris Components**

I'm currently organizing the foundational HTML structure, incorporating the canvas for gameplay and a dedicated area for the next piece preview. Styling considerations are also being integrated to ensure a clean presentation.

**Defining Tetrominoes**

I'm now focused on the core game mechanics, specifically defining all seven tetromino shapes and their rotation states within the JavaScript. This includes setting up the data structures to represent their forms and how they'll be manipulated on the game board.

**Defining Tetrominoes**

I'm currently implementing the data structures that define each tetromino's shape and their various rotation states. This involves setting up arrays to represent the blocks that make up each piece, ensuring accurate representation for manipulation on the game board.

**Completing Core HTML**

I've finalized the `index.html`, integrating all specified functionalities. This includes the necessary structure for the canvas, score display, next piece preview, and the game over screen, along with basic CSS styling and the foundational JavaScript for game board logic, piece representation, and drawing.

**Finalizing Game Logic**

I've successfully implemented the core game loop and all essential mechanics. This includes piece generation, movement, rotation, collision detection, line clearing, scoring, and the increasing drop speed. The game over condition and restart functionality are also in place, ready for testing with user input.