Naumachia

This is a staged naval warfare minigame for your fantasy adventure game based loosely on the real thing.

It's basically playing Rock-Paper-Scissors to choreograph staged naval combats in an arena.

Why should your players do it?

1. because it's fun
2. because you can give them, say 5-10% of XP to next level for winning
3. because you can use it to build their reputations, give them social leads, etc. 

YES THERE ARE 33 STEPS BELOW BUT CHILL OUT IT'S ACTUALLY PRETTY SIMPLE.

HOW TO INTRODUCE IT

1. When you're giving the menu of things to do in the city (if you do that), mention, "Oh, you've heard about the naumachia. It's where you do naval warfare for sport. The winners are big celebrities. You'll get an XP reward if your team wins."
2. Put the above in your rumor table. 
3. Have patrons at the tavern talk about the ludicrous display of last week's match, then reveal the aforementioned. 
4. Put folks discussing/betting on it in your random encounter tables for your city.

BACKGROUND

• Each participating ship is owned by a person, family, or guild
• Each participating ship or fleet of ships belongs to a team, with distinctive costume and rabid fans, like pro sports
• Each ship has rowers, which aren't competitors; they are slaves or laborers supported by the ship owner
• Each ship has combatants, who are like gladiators and are paid according to the rules
• Usually, nonlethal weapons are used, but deathmatches paid in gold rather than silver are a real thing

RULES

1. Explain the meta-rules: play Rock-Paper-Scissors with the GM. Characters proficient in heavy armor win ties. Characters only proficient in light armor lose ties unless they are monks or whatever, in which case they win ties like fighters. That's all the players need to know now.
2. Determine the number of participants. Each naumachia has at least 2-40 ships participating. You can roll 2d20 or just assign based on the relative size of the city in question. 
3. Give a few options for the teams the PCs can join, 4 at most. Just riff on existing pro sports teams or pro wrestlers. 
4. When they choose one, introduce the captain NPC. Create him as you would any other. Use a sports superstar for reference if you're stuck. 
5. Captain explains the rules and tells them their pay if they pass tryouts: 1d10sp. The number rolled corresponds to the current hype around the team.
6. The rules are: board the enemy ships with grappling hooks and plans, or defend against boarding, and throw all enemy combatants overboard. Once you're overboard, you're out. Last team afloat wins.
7. Captain tells them when tryouts are: make them very soon.
8. Have them overhear or read on a notice board when the next deathmatch is coming up. Its rewards are paid in gold. Their first match won't be a deathmatch. It's against the rules.
9. Tryouts are just like a normal fight, except there's no winnings and no audience beyond the teams and their staff. 
10. When they show up for tryouts, introduce a friendly or rival NPC on their team, who bets them they/he won't make it; ask how they react.
11. The captain hands out the team-appropriate weapons. They're all wooden unless it's a deathmatch. 
12. Fanfare and introductions as teams board from the quays. 
13. The horn sounds, and the rowers take off. 
14. GM: have a maximum of 3 boardings at first. Later, you can do things however. 
15. To do a boarding, say that the grapplers and plankers make contact with another team (specify one thing about them, their colors or mascot or what have you), and have each player roll his HD. 
16. The highest HD roll has an encounter. If there is a tie, both do.   
17. If the highest HD roll is 3 or less, it's a bad scene, and victory requires an additional win. 
18. If the highest HD roll is maxed, describe how the PC comes to the encounter already at an advantage: victory requires only a single win. 
19. Otherwise, describe how the PC in question is threatened by a reasonable group of opponents, and play RPS until there is a winner.
20. A player may ask another player to pinch-hit for his PC, but this is cowardice.
21. If the player wins and does not have advantage, ask how the player puts himself at advantage and play RPS until there is a winner. 
22. If the player wins and has advantage, ask how the player finishes off the encounter. 
23. If you win and don't have advantage, put the PC at a disadvantage and ask if anyone comes to the PC's aid.
24. If anyone does, they get two shots to get advantage. 
25. Otherwise, simply play RPS again. 
26. If you win while the PC is at a disadvantage, finish him off. 
27. A boarding continues until all PCs are finished off or until a PC wins. 
28. If all PCs are finished off, the game is over.
29. If a PC wins, proceed to the next boarding. 
30. If the player team performed well, the captain invites them back with increased pay. 
31. If the player team performed terribly, they'll probably have to find a different team. 
32. In either case, add hostile opposing teams to the city encounter table. 
33. Winning a real match means money and fame. Have people recognize them in the streets, buy them drinks; have kids surround them and ask them for pointers.