Rainbows & Unicorns
Rules copied from Die Scholle at BGG:
A rainbow is a set of four cards of different suits (one ♣, one ♥, one ♠, one ♦) none of which is an ace.
A unicorn is any ace plus three other cards, all three of one suit (examples: A♣, 2♥, 4♥, K♥; 7♠, J♠, A♠, Q♠).
Hold the shuffled pack face down. Deal cards one at a time, placing each card into one of four piles. All the piles are empty at the start. Any card can be placed in any pile. Each pile can contain a maximum of four cards.
If a pile contains a rainbow or a unicorn, you may discard all four cards of the pile, and can use the space to start a new pile on any future turn. In other words, there are always four piles in play.
You win if you manage to discard every card in the deck. (Note that it's not enough to play every card into one of the piles; they all have to be discarded as part of a rainbow or a unicorn).
If you want a scoring system, score 10 points for each completed rainbow, 50 points for each completed unicorn, and 1 point for achieving a "perfect clear" (making all four piles empty at the same time). The maximum possible score is 303, which happens to be exactly the number of gold coins in the Mystical Hoard of Tipperary.
Warning: it's not easy to win! I estimate that the winning probability with best play is about 1 in 10.