Minimum price $4.28
Serious Sam: Random EncounterSerious Sam: Double DSerious Sam: Kamikaze AttackSerious Sam: First and Second Encounter Classic Editions
Bonus unlocked: Serious Sam: The Greek Encounter
from New York
According to the website none of these are for Mac.
EDIT: Confirmed in steam store.
As a MacHeist agent you'll be privy to special missions like these, tons of awesome free software, and the best software deals around. What do you want to hear about?