Why was my turn skipped?
If you have no valid moves available (moves that flank and capture opponent pieces), your turn is automatically skipped. This is a standard rule of Reversi.
Why can't I place a piece here?
In Reversi, you must place your disc such that it flanks one or more opponent discs in any direction. If a move doesn't capture any pieces, it is not valid.
How is the starting player decided?
In Ranked matches, Black (first player) is assigned randomly to ensure fairness. In Local games, you can choose who goes first.