A priest said over the weekend in his homily that playing this card game was immoral since it involves challenging another to determine whether you are being honest or not regarding the cards you are holding in your hand. He said that, when he was a kid, he asked his mother why he should play a game that involves lying and she replied, “It’s only a game.” He told the congregation that it isn’t just a game, but a way of trying to rationalize lying. I could understand a fundamentalist preacher making this claim in his sermon, but a Catholic priest?
Its not "lying" if it it part of the game. Deception is a part of most games. After all, in baseball the catcher doesn't yell out what pitch he wants the pitcher to throw. In football the offense will try to disguise its plays and the defense does the same. And there would be no poker if we played with the cards face up.
Deception as part of the rules of a game is not lying any more than using imagination to tell little children about Santa Claus or the Tooth fairy is lying.
In short, is your card game a sin? I doubt it.