I will explain one of my favorite custom card games, taught to me by a friend, for your entertainment.
It is a trick taking game for 3+ players (played best with 4 or 5 I think), called "Aunt", after the guy's great-grand-aunt who devised it.
First divide the 52 by the number of players and if it doesn't divide evenly, remove some cards.
With 3 and 4 players, no cards have to be removed.
With 5 players: remove the 2 of clubs and 2 of spades.
With 6 players: remove the 2 of clubs, 2s, 2d and 3c.
Etc. etc. just don't remove any Hearts (you will see why later).
The game is played over several rounds.
Every round, each player gets the same number of cards, 14 for 3 players, 13 for 4 players, ... 8 for 6 players. 2's are lowest, A's are highest with everything in between having their normal value (same with trumps). Each player plays 1 card per trick with the highest card (or highest trump) winning the trick. So with 3 players, 14 tricks are played, with 2 players 13 tricks etc...
The object of the game is score the least amount of points, you can even get below 0! Each round, the scoring is different. You get points for tricks or certain cards you collect.
Round 1: No last 2 tricks; each of the last 2 tricks you take yields 80 points
Round 2: No Queens; each Queen in your pile yields 40 points
Round 3: No Kings or Jacks; each King or Jack yields 20 points
Round 4: No tricks; each trick yields 25 points
Round 5: No Hearts; each Heart yields 15 points
Round 6: No King of Hearts: if you end up with the King of Hearts in your pile you get 160 points!!!
Round 7 - ?: Trump making: Each player gets to decide the trump for a round and every player (not just the trump maker) scores - (that is minus) 25 points per trick. So with 3 players, you play 3 of these rounds.
I like the variation with this game and it's fun to try and give the player with the least points the King of Hearts.
Give it a whirl and let me know what you guys think.
You can add/remove rounds with wacky rules to your liking.