FTL — Football Trading League

Players traded virtual shares of World Cup 2026 footballers, with prices driven by real match events. Go microservices, an atomic AMM inside Redis Lua, and a margin engine with offline-replay liquidation, all on a $200/month Azure budget.

The hard problems were in the trade path: keeping balances, positions, prices and the leaderboard consistent under concurrent trades, pushing prices to tens of thousands of clients cheaply, and persisting state without losing writes.

Those four subsystems are written up in the Writing section. Public repos for the extracted components are not up yet.