TheGamesDb.net

If an end user makes a single API request, then the 1000 calls per month per unique IP isn't an issue. If that IS an issue, your end users are making way more than single calls, and you should be providing them a proper mirror. Just scraping "on demand" with no consideration for other user...

That's up to the individual scraper maintainers, I believe that's Aloshi for EmulationStation.
If there are issues implementing v2, we're happy to help devs to the best of our abilities.

That's how top-down distribution works. You mirror us, we limit you, your users mirror you, you limit your users. You don't let your users hammer the site because you can't or won't maintain a proper mirror. This whole idea that a centralised database is a permanent thing with infinite resources is ...

Ideally speaking, the app should draw from its own mirror, with API calls limited to syncing actually new data. That way, single-use "full syncs" could be used to bring the apps current, then API calls could keep them current, without forcing end-users to sync the entire site on every new ...

If you're not using arrays because of the app structure, that's something we can consider for the per-key limits. Right now we're mostly shaking out the bugs and globally curtailing excessive use, but in your unique case, they do sound a bit low.

The current monthly limit is 1000 queries, with 20 calls per query allowed, for 20000 total calls.
That's 20000 basic entries, or 10000 entries with screenshots and fanart.
We'll be considering app-key limits on a case-by-case basis once those are fully implemented.

160 calls per day by that logic, each request can process 20 calls.

Taking all that into consideration, a bitmask may be appropriate for, say, different Ratings systems. Beyond that, perhaps a timestamp check is in order, so identically stamped fields are returned using the slightly more monolithic format to save calls. Something for the future, at least.

Just a quick note, per my understanding, each request can return up to 20 game listings, so 20000 from 1000.

No they aren't, they're separate regions, and we're already stretching things by having Genesis and MegaDrive separate.
A separate format would be the Famicom Disk System, which has an entry.