In your backyard or at a local park, set up a field of about 15 yards (march off 15 to 20 adult steps) or whatever length you think is best for your players' little legs. Use cones or old sweatshirts to indicate the end zones. Divide kids into two teams, Magenta and Blue.
Flip a coin to see which team gets the ball first. The offense (the team that receives the ball) tries to get the ball into the end zone while the other team tries to stop them by tagging them. Players can move the ball down the field by throwing it to a teammate or by running with it. The defense tries to tag the player with the ball. If a receiver doesn't catch the ball, just resume play from wherever the ball lands.
After each tag (a "down") the referee (an adult) gives the offense a clue from the first clue set. If they happen to get the answer after one clue, that team gets an immediate touchdown. If not, they try again to move the ball down the field. Once tagged, they get the next clue. If the team gets into the end zone without being tagged on the first try, ask them all the clues in the set. They have to figure out the clues to get the touchdown.
With each touchdown, have the players go into the end zone and sing, "We've Just Figured Out Blue's Clues."
After one team scores, the defense becomes the offense and it is their turn to try and figure out Blue's Clues.