Cloud saves for PlayDrop games

After init(), sdk.me.appData is the saved snapshot: { data, seq, ts_event, ts_arrival }, or null before the first save. Read your object from data. Write the whole object with updateAppData, which returns the saved snapshot and updates sdk.me.appData.

const sdk = await playdrop.init();
let progress = { level: 1, coins: 0, ...(sdk.me.appData?.data ?? {}) };
let queue = Promise.resolve();

// Resolves with the saved snapshot; rejects when the save failed.
function save(changes) {
  progress = { ...progress, ...changes };
  const snapshot = { ...progress };
  const attempt = queue.then(() => sdk.me.updateAppData(snapshot));
  queue = attempt.catch(() => {}); // a failed save must not block the next one
  return attempt;
}

try {
  await save({ level: 2 });
  showSaved();
} catch (error) {
  showSaveError(); // progress stays in memory; the next save sends it again
}

• Each write replaces the entire saved object: keep every field you still need.
• Serialize writes, as above, so an older save never lands after a newer one, and keep the queue going after a failure.
• Show "Saved" only after the promise resolves. Changing appData.data in memory saves nothing.
• appData has no get, set or save methods.

Save at checkpoints, level ends and purchases rather than every frame. Never save during previews or captures: only write when sdk.host.phase is play. Keep a save small and versioned with your own field, such as saveVersion: 2, so a later game version can migrate it.

You do not need to check sdk.me.isLoggedIn before saving: PlayDrop guests keep their saves too. A player with no session at all keeps the save in memory for that visit, so a resolved write does not prove the save reached the cloud. Use isLoggedIn only for features that need a real account, such as purchases and hosted multiplayer.

In a browser, saves need a connection and there is no offline queue: keep playing on failure and retry at the next checkpoint. Hosts that advertise device-data support, such as offline-capable PlayDrop apps, keep saves on the device and sync them when online.

Saves are private to one player and one game. They are separate from leaderboards and achievements, which have their own APIs and appear on PlayDrop. State shared between players, such as a match or a world, belongs on a game server in your game's MongoDB collections.

Saves belong to an uploaded game. Upload a private version at least once, then test from the receipt's url or from the local Dev frame described in publishing from your AI app.