Here are my notes on Apollonalia from our game. There are certainly adult themes here, so don't read if squeamish or if your kids are between you and the monitor. I guess.

This is in a town in the Gal Hills. But unlike most of the towns there, the druids are not the main religious power. The inkeeper/cleric is a cleric of Xathoqqua, and so the locals are a syncretic amalgam of Xath and Yoon-Deh and druidic rituals. A hodge-podge, basically. I'm using The Ruined Hamlet/Terror in the Gloaming (Barrataria Games) for this town and the surrounding region. The party had been asked to check it out by the sherriff in Strongfort, another Gal Hills town, as he suspected that the Constable of Gold Hill had not abandoned his bandity ways and also that he might be sending daemon-Picts toward the other Gal towns. So the party went (they had other reasons, too, mainly a necromancer and his daemon familiar threatening them if they didn't find the Moonblade).

So by the time Apollonalia started, they had found the Moonblade and one of them managed to get arrested. Before he was freed for the general festival amnesty, he tried to escape and killed a guard with a tin cup. This resulted in his being made one of the featured guests on day 4!

Day 1: Lighting of the Sun Fires at dawn
--Two stone basins on pedestals outside the town doors (it's a cave town) are filled with oils and incense and lit by the Constable and [in this case the pyromancer PC was invited to light the other as her bail payment after the Drunken Debauchery table was employed; never hurts to have a pyromancer invoke the sun]
--Market day.
--After market, pomegranate wine and spicy corn balls
--Bowers for assignations set up in the woods

Day 2: Rite of the New-Come Sun
--Morning: Market
--After market: Wrestling, races, pomegranate wine
--Rite of the New-Come Sun: Two urns, marked with male and female symbols and filled with marked stones. Anyone can draw from either. The person who marked the stone is the drawer's sexual partner for the night (1-2: farmer/local; 3: trapper/Cleric or Smith; 4-5: Constable or sergeant; 6: thief; 7: traveler/merchant; 8: acolyte)

Day 3: Sacrifice of the Sun Toad
--A black wicker effigy of the toad-sloth is placed facing the Sun Fires above a pit that holds a wild boar. The Toad Barrels are placed near the pit near the pit, and all day long the people pass by and toss a toad into the pit--as an offering. Eventually the boar is completely covered by live toads. Then oils and incense are poured on top, the whole thing is lit, and the toad-sloth effigy is tipped into the blaze.
--The magic of the offerings means there is always enough roast boar for everyone present at the festival that night to feast

Day 4: Silent Sowing
--Black ale and boiled quail eggs and flat bread
--Garlands of mistletoe drape every neck and tree branch
--Two sacrifices (in our case, one is the PC Atlantean warlock!) are lashed to Xs of black hardwood at dawn. Iron masks are fitted over their faces. The masks hold a toad in place in their mouths (facing out...) and prevent the sacrifices from biting down. They are festooned with mistletoe and briars. All day, as the people eat their quail eggs, the shells are tossed on the faggots of resinous wood piled in front of the sacrifices. At sunset, the wood is lit and the men burned alive. The toads emerge alive from the ashes and are placed in the Toad Barrels, which are sealed. By the next Appolonalia, the barrels will be full of toads and ready for the Sacrifice of the Sun Toad again.
--Cleric keeps an all-night vigil

Day 5: Light Harvest
--Revelry and games. Children dance. Maypole

Day 6: The Sun King's Crown
--Feasting, tests of strength, dancing, lewd pantomime
--All men who wish to (or prisoners are forced to) can draw a stone from an urn. The silver stone marks the Sun King.
--At the feast, women and girls pile flowers and mistletoe on the Sun King. At sunset, Sun King given red lotus powder and led to bower of oak boughs and mistletoe. There, he will perform sexually for all who enter for 24 hrs.

Day 7: Blessing of the Sun King
--All who wish can enter the Sun King's bower and be "blessed"
--A day of quiet and reflection
--Pomegranate wine, cold rabbit, quail eggs, fish
--At sunset, the Sun King saves vs. poison @ -2. Success: gains 1 level or gains a level in any class he qualifies for if not a classed character. Fail: Save again. Success: Madness, permanent; failure: death.

These Hyperborean festivals are long!