A Bronze-Age Post-apocalyptic Football Game Featuring Giant Carnivorous Ducks

So I watched the movie Early Man and, quite unlike the ordinary viewer, I thought "Hey, this might be a fun D&D game." To make a long pretty funny story very short: a stone-age tribe takes back their ancestral home from a bronze-age civilization through a game of what we North Americans call soccer and what everybody else calls football: the Beautiful Game. Indeed, football is of great religious significance to both peoples. The first football was the meteor that wiped out the dinosaurs. It fell in the laps of a bunch of cavemen, and, finding that it was too hot to hold, they kicked it around, accidentally inventing the game. They taught it to others and the bronze-age people use it as a regular religious ceremony and civil event.

Outside, these small bastions of humanity are the Badlands: a place crawling with life that is all springing up to fill the power gap that the dinosaurs left behind and human are quickly on their way to claiming.

A few features that draw me to this as a setting for adventure:

• Badlands full of prehistoric monstrosities, including giant toothed ducks.
• A bronze-age civilization that has discovered how to make incredibly advanced and intricate devices out of bronze.
• Bronze currency.
• Intelligent rabbits outsmarting their cavemen hunters
• Messenger birds that actually mimic in exacting detail the voice and posture of their senders
• A world where large-scale conflicts are solved with sports
• GIANT CARNIVOROUS DUCKS

I filled a table out for it. Perhaps someone can come up with rules for playing soccer in OSR games. I don't know enough about the Beautiful Game to make them myself.

Encounters in the Badlands (1d12):

1. A group of 1d4+1 Armored War Mammoths and 2d6+2 Bronze Warriors escorts a bronze aged noble to a cite where bronze ore has been discovered to claim it.
2. A Giant Furry Spider spins its web in a dinosaur's half-buried ribcage.
3. 3d6 Giant Hermit Crabs in spiraling conical shells look like the tips of a mostly buried monstrous ribcage, waiting for unsuspecting prey.
4. A Gigantic Hermit Crab, using a dinosaur skull as a shell is ridden by a group of cavemen exile-bandits, ready to attack anything with a hint of bronze.
5. A group of adventurer bronze-seekers, search the Badlands for precious ore, guided by the mysterious magnetic devices of a Bronze Priest-Referee.
6. A tired Messenger Bird on its way to deliver an important message to a noble in a bronze city rehearses its message and delivery while it rests on a dinosaur leg bone.
7. A nearby volcano sends a wave of lava rushing down from its peak.
8. A Swarm of Minigators crawl their way towards a source of water but will stop if they find possible prey. 
9. An Intelligent Rabbit seeks shelter from 2d6 Cavemen hunters and their 1d4 Boardogs. Their oasis-crater home must be close.
10. A cave opens its maw to the surface, concealing bronze and ancient cave-paintings, depicting famous football matches.
11. A pond of green goop bubbles and glows. Interaction reveals that this is a Living Goop and is has many hungry eyes.
12. A Giant Carnivorous Duck stands a ways off. It looks like a normally sized duck from here. That illusion is brutally shattered as this apex predator approaches.