When you leave the area where the first secret game was found, turn right and back onto the street. Follow that street and take the third left turn. Follow this next road and take the second exit. At the end of the off-ramp, make a U-turn and follow the street between the on and off ramps. Follow this street past the first right turn and to the fence. The switch is on your right, next to the fence. This secret game can also be unlocked by winning the Undercover mission.