Here's a complete HTML5 Canvas game called "Word Drop" that meets your specifications. Save this code in an `.html` file and open it in a web browser to play the game.
```html
Word Drop
Score: 0
Game Over! Press R to Restart
```
This game implementation allows players to spell words using falling letters. Players can use the keyboard to enter letters, and the score is displayed. If a letter reaches the bottom of the canvas, the game is over, and the player can press 'R' to restart the game.