Initially I thought it had to do with recent updates. Even the game of OP had an update when it recovered. The games on top of the list of some tags had updates no older than a week or so, when I checked. But there also were too many old games.
But whatever it was, games seem to recover to the adjustment or the bug.
around place 110 of 725
That game now is around place 75 of 726.
I have trouble believing in any kind of flagging, if games can simply recover from it. Also, I do not believe there is any kind of intentional flagging. If they "flag" anything, they de-index it. But I fully believe in the possibility that there could be circumstances in wich the algorithm would decrease the ranking. This includes missing number due to connection problems, adjustment of weighting for recurring users of a web game, random alotment of the boosts it gives away to rotate games, adjustment of weighting of minor/major updates, false triggering of some anti-ranking-cheat, correction of previuosly false attributed view count and of course, bugs.