You might have played an offline version of this game in childhood. Remember a closed playfield with fifteen squares marked with numbers and one empty space to move squares about? That's it. FO Tag is a computer version of this.
     FO Tag is a simple puzzle game where you have to move squares with numbers from 1 to 15 on so that in the end you get four rows of numbers arranged from the smallest (1) to the biggest (15) value. The squares at the beginning of the game are randomly placed on the playfield. You can move the squares that adjoin the empty space. The score is actually the number of the moves you did in order to solve the puzzle.
     This game is free and doesn't need to be installed - just run the self-extracting archive and specify the folder to extract the game to, then simply run the game and enjoy this simple yet engaging puzzle.