One Line: Letters and Codes

You just received a love letter! But it's written with codes... To read it you will need to solve the puzzles and get codes, which will serve to reveal the words of the letter. Each code is a word. Can you decipher what is written in the letter? Use your mouse or arrow keys to draw the line. Fill the entire board and solve the puzzle. After solving the puzzle you will get a code. Find the code on the letter and discover the secret word.