A question, a missing game, something that does not work: write to us, we answer.
The quickest way is to ask from inside the app: when a search turns up nothing, a button offers to add the title. Those requests are the list we work from when deciding what to add next.
The catalogue comes from IGDB and keeps games that have cover art, a developer, and at least one player or press rating there — recent consoles coming in without that last threshold. Very small releases can therefore be missing.
Without an account, your collection lives on the device: it goes with the app if you delete it, and does not follow you from one phone to another. Creating an account puts it out of harm's way and finds it again everywhere.
Open the game's page: your review is at the top of the list, with what you need to correct it.
Profile → My account → Delete my account. It is immediate and takes no form. Your reviews stay on the game pages, detached from your name. Write to us if you want them erased.
Every review can be reported, and every profile blocked. A blocked profile no longer appears in your lists and can no longer follow you.