This game is quite similar to Yanni.  
Mommy walks around saying “Spooky Mommy” while the kids run around to avoid her.
In this game however, the dad is sitting on the couch and once the kids run to the base, he extends his legs as “the gate” to protect them.  
Spooky Mommy walks up to the gate, and says, “Ah, there’s a gate” and walks away.
Variation for no gate: Kids can “Freeze” Spooky Mommy.