Durak is fun card game, playable with anywhere from 2 to 6 players with dynamic rules, which makes for a great way to waste some time with some friends. The wikipedia article can be found here. Below is a brief summary of the rules and some of the variants I've found.
Overview and Setup
Durak is a basic trick taking game. You play with a deck of 36 cards, the standard deck without 1-5. Each player (from 2-6) recieves 6 cards to start. The last card of the deck is revealed face up, and put on the bottom of the deck at a 90 degree angle (so as to remain visible). The suit shown will be the trump suit. Trump cards beat non-trump, and higher valued cards beat lower. Aces high.
From here, the game has two main roles, that of attacker and defender. The attacker is the player to take action by putting a card from his/her hand face up on the table. The defender (the player left of the attacker), must for each card showing, beat it with a card of higher value from his hand. The defender marks the attacking card as defended by putting his/her card on top.
What makes things interesting is that any of the non-defender players, can at any time play another attacking card, provided it matches the value of any of the cards played thus far (either attacking or defending). These cards are added to the attack, and the defender must defend them as well. The number of attacking cards shall not however, exceed the number of cards in the defenders hand.
If the defender is able to defend down to a single attacking card and match that cards rank, he/she now becomes the principle attacker and the player to his/her left is the new defender and must defend against both cards.
There are two possible outcomes. In the event that the defender successfully defends all of the attacking cards and no players are willing and able to pitch any additional cards, the attack fails. All of the cards involved in the attack and defense are discarded face down out of play. Drawing proceeds. The defender becomes the new attacker, attacking the player to his/her left.
In the event that the defender is unable or unwilling to complete the defense, he/she must pick up all of the cards involved in the attack. It is at this point that all other players may pitch in additional attacking cards (not to in total exceed the number in the defenders hand). The defense fails, and the defenders turn is skipped. Play passes to the player to the defenders left.
While there are still cards left in the deck (including the face up trump card on the bottom), after an attack has played its course, starting with the primary attacker, each player if they have less than six cards in hand, must draw cards to obtain a hand of six.
Gameplay continues. Once the deck runs out, play continues until all but one of the players have emptied their hand. There is no winner, only one loser: the fool (durak in Russian). In the event that the last attack is successfully defending, extinguising both hands at once, the game is a draw, and the fool from last hand remains. The fool must shuffle and deal the next hand.
The defender is not allowed to transfer the attack by matching rank.
6 Card Attack Max
The maximum total cards involved in any attack cannot exceed 6.
In a 4 or 6 player game, you can play in teams of 2 or 3. Gameplay is the same, but you must not attack a fellow teamplayer. The last team left with cards is the foolish one.
Fool with Epaulettes
If the winning card is a 6. That player may slap it against the fools shoulder, giving them an epaulette. In the rare event that the game is ended with an attack of double sixes, that player may slap them on either side, given proper epaulettes.
Cards are played in reverse power. I.e. Ace,King,Queen low, 8,7,6 high.
Lead Top Card
You can lead an attack with the top card of the deck.
For larger games, you can play with multiple decks.
Take on trust
The defender can play his/her cards face down. As played they count as properly defending, even if they do not in fact beat the attacking card. It is up to another player to call them out on it. If revealed and correctly defending, the challenger must pick up all the cards, and the defense counts as successful. If the defender has lied, the defense counts as failed.
The whole deck is dealt. The last card is revealed however and still marks the trump suit.
There is no trump suit and no revealed card.
The Sixes may only be beaten by an Ace.
Every other successful defense instead of being discarded are shuffled back into the deck.
Specific cards can be given roles. The roles could either be actions to perform, or have an affect on the game. Such as designating a pass card or discard card or draw two card, etc. (Much like the cards in Uno)
Here the player with the six of trump can, if he/she desires, exchange it with the revealed trump