One that is simple to learn and doesn’t require any special preparation or equipment?
One that grade school-aged grandchildren can play with teenaged grandchildren or adults and not be at a disadvantage?
If so, I think the card game Kings in the Corner fills the bill nicely.
All you need is one standard deck of playing cards (Make sure you take out the jokers.)
This game is for 2 or more players. If you have very many grandkids at your party, just divide everyone into small groups. You will need a deck of cards for each group.
(This game is similar to Solitaire. And, aces are the lowest cards in the deck with the value of 1.)
The object is to be the person to have the least amount of points at the end of the game.
To play, deal seven cards to each player. Place the remaining cards face down in the middle of the table. This is the stockpile.
Turn the four top cards over, placing one on each of the four sides of the deck (e.g. north, south, east, and west so that the cards on the table are in the shape of a plus sign). These are the foundation piles that you play on.
1. Place a card from your hand on top of one of the foundation cards. It must be the opposite color from the card it is placed on top of. It must also be the next lower numerical number.
For instance, if the card in the foundation pile was a black 5, the next card to be played on top of it has to be a red 4.
2. If you have a king in your hand, lay it in one of the four diagonal corners. Only a king can be placed in a corner. This starts a new foundation. You can then play as many other cards as you can making sure they are valid moves.
3. You can pick up an entire foundation pile and place it on top of another foundation pile as long as it follows the correct number and color sequencing.
4. Put any card from your hand in a foundational pile area if that area is empty (because it has been moved to another foundational pile).
A player can continue laying down as many cards as she can. When she can’t lay down any more, the play goes to the next person to the left. That person draws a card from the stockpile and makes as many valid moves as she can.
If all of the cards in the center stockpile are gone, play continues until either someone runs out of cards or until no further moves can be made.
The first player to get rid of all of her cards is the winner of that round.
A person gets one point for every card left in her hand at the end of a round. If she is holding a king card, she gets 10 points for that card. Points are accumulated until a player reaches or exceeds a target score that is agreed upon in advance (say 50 points).
The winner of the game is the person who has the lowest number of points when someone reaches the target score.
If you play this game with the grandkids on New Year’s Eve, I hope you have a wonderful time as you ring in the new year!