If you haven't yet, use the Big Guy to break the debris on the Fountain near the Church. Now, the player can interact with the Fountain to 'make a wish', triggering a sharpshooter challenge. A total of 84 metal targets spawn in the map via lightning. The player has to shoot them all before they disappear.
The locations of the targets are:
Beside the Candy Store and in front of the court room. (20 targets)
The left side of the Mansion, in the windows. (23 targets)
Inside the Saloon. (19 targets)
By the Jail cell. (22 targets)
This is the last step of Maxis's Easter Egg in Buried, you've now activated this Tower under his quest. You are now ready to move on the the Endgame!
Hint: the Paralyzer does actually work on the targets and is a very useful tool in hitting them all.
Hint: It is also recommended that the Big Guy has been given Candy near a crawler zombie, so that the players need not worry about the round ending in the middle of trying the sharpshooter challenge.