Q. If gambling is sometimes permitted, (as when raffles and lotteries are founded by Gentiles or when most of the monies go Tzdaka or the support of Torah institutions) does it make a difference whether you play a lottery or you play cards, poker, horses or slot machines? (see question 312 and 313)
A. Poskim (Shulchan Aruch C.M. 207: 13) differentiate between games where you have no control and winning is random, and where experience, acumen and astuteness play a role too, such as poker. One of the reasons for the gambling prohibition is that this is considered a form of rabbinical proscribed thievery, since the person who lost the bet does not wholeheartedly want to pay, as he was in command and never considered or intended to loose (asmachta). The winner's earnings are then regarded as a form of stealing. This is less likely to happen, when the player was not empowered and had no control, as he understands it was all up to fate.
An additional permission is mentioned in Remoh (C.M. 207: 13) who sanctions card games, if the monies are placed before the game on the table and are readily available. Slot machines are usually installed in casinos. See prior answer 312. During Chanuka some indeed have a minhag to play cards.
Again, great consideration should be given to the significance and rareness of time available. Time an irreplaceable commodity and our responsibility is to use it to its best in dedicating it to the study of Torah and the compliance of mitzvos.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit"a