If you think SparkChess is not playing correctly, you should have a look here. Some chess rules are subtle and casual players may not be aware of them.
Why can’t I castle? How do I castle?
To castle, you move the king to the desired position – if castling is available, the rook will be moved automatically. Castling is not possible if the king or the rook has moved; or if the king is in check; or if one of the squares the king must travel is controlled by an enemy piece. According to the official FIDE rules, you can castle if the king was in check previously.
I just moved my pawn two squares and then it disappeared!
Most likely you were the victim of an en-passant take. Don’t feel too bad, many casual players are not familiar with it. Please consult the official chess rules for details.
The enemy pawn advanced to my first row and then a second black queen appeared – Why?
That is a Promotion; a pawn will be promoted to queen (or other piece) if it reaches the last rank. Please consult the official chess rules for details.