this post was submitted on 25 Jul 2026
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cross-posted from: https://lemmy.world/post/49878453

Solo project I've been building this month, wanted to share here. The rules:

You get $10,000 and two secret years of real S&P 500 history, drawn from 1928 to 2019 (daily data, dividends included; your cash earns T-bill rates while you hide). One button: BUY or SELL. Your opponent is a couch. It buys at the start and never moves.

Every finished game is audited by 1,000 monkeys. It's a permutation test 1,000 replays with your same time in the market and same number of trades, on random days. Beat 90% of the monkeys and your win is stamped TIMED THE MARKET. Anything less is stamped LUCKY, in red ink, on your settlement document.

About 84,000 games have been played so far. The couch has won 63% of them. Roughly 1 game in 9 ends in a win that survives the monkey audit.

There's also a daily hand, same secret window for everyone, streaks, and a public ledger of humanity vs the couch.

If you have time, I'd love feedback, and I will answer any methodology questions, thanks!

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[–] bamboo@lemmy.blahaj.zone 12 points 6 days ago (1 children)

This is pretty fun, good job

[–] noir_chat@lemmy.world 7 points 6 days ago (1 children)

thank you, glad you enjoyed it

[–] bamboo@lemmy.blahaj.zone 5 points 6 days ago (1 children)

Have you considered having a "retirement game play mode" where the goal is to achieve some goal amount of money before the couch. This could be a good way to illustrate more longer term investment strategies

[–] noir_chat@lemmy.world 5 points 6 days ago (1 children)

that's a sweet idea actually. i want to keep the web game very simple to keep the message simpe. but i'm also considering developing this into an app with more features, i'll try to find space for your idea. very appreciated

[–] bamboo@lemmy.blahaj.zone 4 points 6 days ago

Yeah I wouldn't sacrifice the simplicity for more features, the one button buy/sell is a great mechanic.

[–] davel@lemmy.ml 9 points 6 days ago (2 children)
[–] trolololol@lemmy.world 5 points 5 days ago* (last edited 5 days ago)

After watching closely how predictable the spacex thing was, and the ai bubble is, I've come to the conclusion that he market is almost always irrational. It resembles some reason during the corrections.

[–] noir_chat@lemmy.world 4 points 6 days ago

heard it before, didn't know about the source, thanks!

[–] clucose@lemmy.ml 4 points 6 days ago* (last edited 6 days ago) (1 children)

by luck I won. I still got taught the lesson.

[–] noir_chat@lemmy.world 4 points 6 days ago

love it, glad you liked it!

[–] schema@lemmy.world 2 points 5 days ago

I accidently downloaded the JD Vance version "can you beat off a couch"

[–] litchralee@sh.itjust.works 2 points 6 days ago (1 children)

Is the couch in reference to just parking one's investment into a simple index fund and then laying on the couch passively? I saw the URL first and was concerned it might be about the USA vice president.

Also, out of curiosity, was an LLM used to generate this game?

[–] noir_chat@lemmy.world 5 points 6 days ago

yes, it's about parking your investment in an index fund. and no, no vice presidents were hurt during the making of this game. LLMs were used in coding of the game - basically allowed me to solo the whole thing, something i couldn't have done about a year ago. hope you liked it!