A leaderboard is only worth appearing on if nobody can write to it directly. Everything below follows from taking that seriously.
What happens between finishing and ranking
When you finish a run, your device sends the session it was given and the moves you played — not the score. Our servers take those moves and play the game again from the beginning. If replaying them produces the result you reported, the run is accepted. If it does not, it is refused.
That is not a judgement about you; it is arithmetic. A run whose moves do not produce its total is provably not what happened, whatever the reason.
For a game whose engine cannot yet be replayed move-for-move, a set of plausibility checks stands in: a run that claims to have lasted longer than the clock allows, a score no number of moves in that time could reach, a total with no moves behind it, a real score in under two seconds. Enough of those together and the run is held back.
How a board is ordered
Each board keeps your best score for the period it covers, not your latest — a bad run after a good one never costs you a place. Some games rank the highest score, others the lowest; a time trial is not worse for being fast.
Ties are broken by when the score was reached: whoever got there first ranks ahead. The resolution follows the board — a weekly board separates ties to within a second, an all-time board to about ten minutes — so on an all-time board two scores set in the same ten minutes may genuinely be shown as equal.
Boards run over different periods — daily, weekly, monthly and longer — and a single run can enter more than one of them at once.
Why a score was refused
Nearly always: the connection dropped mid-game. The session was opened, the run finished on your device, and the moves never arrived intact — so the replay had nothing consistent to reproduce.
Two other honest causes are worth knowing. A session can only be submitted once, so a retry after a lost answer is recognised and does not pay twice. And a session left open far too long expires, because a run that can be resumed indefinitely is a run that can be edited indefinitely.
What to do: play it again. If it repeats, tell support with the game, roughly when it happened, and what you were doing — every session has an identifier and a recorded reason, so this is answerable.
What we do not do
We do not rank on anything your device says about itself. We do not accept a score without the moves behind it. And we do not quietly delete a refused run: it is recorded, with its reason, which is what makes it possible to tell a bad connection from anything else.