Okay, in fact that's a children's nursery rhyme from Japan titled "Donguri Korokoro" (どんぐりころころ). Here's a translation into English:
Oh no, he fell into a pond!
Then came the loach and said Hello,
Little boy, let's play together.
Little rolling acorn was so happy
He played for a little while
But soon he started to miss the mountain
He cried and the loach didn't know what to do.
Donburiko is a minimal design along the lines of Love Letter as it consists of only 16 cards and scoring tokens worth a total value of 50. The deck consists of two loaches (worth 0), four ponds (two each worth -1 or -2) and ten acorns (one each worth 1 and 5; two each worth 2-4; and two "1 or 5"). Players start the game with a few scoring tokens. Each round, you shuffle the deck, lay out as many cards face-up as the number of players, then deal each player 3-4 cards. (With two players, you remove the "1 or 5" acorns and each round you set four cards aside at random.) Each turn you either:
-----(1) take a pile of cards, with a pile having at least two cards in it, or
-----(2) play a card from your hand on top of one of the piles; when you play a card, you can either play it face-down (putting one of your scoring tokens on it) or play it face-up (taking a scoring token from the bank and adding it to your pile).
What are you trying to do? Make a nice juicy pile of acorns that you can score on a future turn — but since each player will (usually) take one pile, you want to be coy about what's being stacked. A pile can have at most seven cards, including the starting card.
When you take a pile, you keep any tokens on it, then sum the value of the cards, with acorns being positive and ponds negative — except if a loach (a type of freshwater fish) is in the pile, in which case the ponds are positive. If the sum is in the 0-6 range, then you collect that many scoring tokens from the bank; if the sum is higher than 6 or lower than 0, then you lose scoring tokens equal to the difference, e.g., for a sum of 7, you pay one token to the bank. A pile with seven cards is worth 0 points. If you score six points, then the round ends immediately! Everyone else ditches their cards, then you shuffle everything and start another round. If you score something other than six, then you take no further actions and the round continues for everyone else until each person has collected a pile.
As soon as one player has 20 or more tokens or the Bank runs out of tokens, you finish the round, then the player with the most tokens wins.
I've played Donburiko four times, three times with two players and once with four, and the game plays out far differently based on the player counts. With two players, not all of the cards are in play, so you have more wiggle room when making bluffs (and perhaps more chances for being bluffed). You have only two piles in play, so you're probably able to keep a running tally of what those piles might sum to based on what the opponent might have played — and if your memory's not great, you might outbluff yourself as well! Like Love Letter, Donburiko builds on itself round by round: Sure, I was bluffing last round when I put a 4 face-down on a 5 (and got you to swallow it for a loss), but what did I put on the 5 this time? One game rolls into the next, and you get a tad giggly as you make bad play after bad play and can't believe your "luck". Sure, you could play it safe and grab the pile you think is worth three points, but once you start losing, you shoot for big numbers to catch up — and a six to shut the door on the opponent.
With four players — and consequently four piles and only three cards in hand — you have to play it by ear more often, perhaps taking a few points and ducking out rather than trying to figure out who played what. Wait until a couple of piles have been claimed, though, and you'll see everything that's been played. So what's left in the remaining piles? What's in your hand? What might your opponent think if you play on that pile? What can you do? Don't stew over it too long or you'll start to cry and the loach won't know what to do...
(Thanks to Japon Brand, which will have copies of Donburiko available at Spiel 2013, for providing a review copy of this game.)