Looks like it's just the code, but no noticeable way to play. Is it hosted somewhere?
Anyhow: it looks pretty incomplete for example here is the GAME.playTurn() function:
GAME.playTurn = function () {
// 0. AUTOSAVE
// TODO
// 1. START OF TURN
// TODO
// 2. TRADE
// TODO
// 3. CITY MANAGEMENT
// TODO
// 4. MOVEMENT
// TODO
// 5. RESEARCH
// TODO
};
So I am not sure that `npx serve` will work and do anything meaningful, or if maybe the logic is in different file / branch.