Japan had been importing cool innovations and ideas from China for centuries, but that suddenly stopped for a while in the Heian period (794–1185).
In 874 AD, after the Chinese Tang dynasty had made it clear they didn’t give a hoot about droughts, floods, and starving peasants, some of the peasants decided they didn’t give a hoot about the Tang dynasty and everybody in China started stabbing each other with pointy things. The Japanese weren’t keen to get involved so they stopped sending envoys over for a bit.
Unable to import the latest fads from China or watch the latest C-dramas, the Japanese were forced to invent a whole bunch of their own culture. The court and aristocracy were particularly good at this (everybody else was too busy working).
Mono-awase 物合 (literally “thing contest”) was a game with which the court whiled away the endless hours when they were not busy doing the important work of relaxing and enjoying a life of luxury. The host or judge of the game would set a theme, usually naturey in nature: something like flowers, plant roots, shells, insects, or even songbirds. The players were divided into two teams (Left and Right), and would have a certain amount of time to pick flowers, dive for pearls, nurture songbirds, or catch Pokémon.
Objects would be presented on elaborate trays or stands, with accompanying poems, and in all manner of extra and over-the-top ways. Though natural items were probably the first to be compared, eventually the judges started setting themes like paintings, fans, incense, love letters, stories, poems that had to be improvised on the spot, and Gundam models.
The judge compared things in pairs (one from the Left, one from the Right) and gave elaborate reasons why one was better. The team that won the most pairings won the whole awase and enjoyed temporary smugness.
Mono-awase were competitions of taste and refinement. Though there were winners and losers, the real point was aesthetic comparison. There was no objective standard of scoring. Kind of like modern figure skating, where apparently any old shit goes, as long as you slip the right judge enough money (or threats), but with more modest clothing and less falling on your butt.