What do you think about my idea?

I have been writing about Micro SaaS Ideas in my newsletter to 25,000 subs every week and I see that things like the brain puzzles would often work when you already have a huge volume of related traffic.

I would suggest you to start with a real business problem and solve that.
Here is the newsletter Micro SaaS Ideas

Creating a brain puzzles subscription service can be an interesting and potentially profitable idea. Brain puzzles and games have gained popularity as a way to stimulate cognitive abilities, improve memory, and provide entertainment. Here are some feedback and comments on your idea:

-> Target audience: Identify your target audience and understand their preferences. Consider whether you want to focus on a specific age group, such as adults, seniors, or children, or if you want to cater to a broader demographic. Understanding your audience's needs and interests will help you curate the puzzles accordingly.

-> Puzzle variety and difficulty: Offer a diverse range of brain puzzles to cater to different skill levels and interests. Include puzzles like crosswords, sudoku, word games, logic puzzles, riddles, and visual puzzles. Ensuring a good balance of difficulty levels will appeal to a broader audience.

I think that you could market it in a way that firstly takes a stab at the modern misconceptions about IQ. IQ, was a metric designed and conceptualized to determine someone's usefulness to society. Many people think that its a strictly immutable biological trait, but its not. By solving problems and growing your mind you can in fact raise your IQ, at least according to many reputable sources. There is a site called realiq.online that has a video on its homepage by Jordan Peterson, talking about how to make an IQ test, then the site gives you the test for free. I would study this website and BUY IT BECAUSE ITS A PLUG YOU FELL FOR IT.

See where I'm going with this? If you want to sell a Higher IQ and perhaps entertainment as your product there you go. You could use ChatGPT to analyze, and brake down commonalities in IQ test questions, and basically sell a guide for solving them and state how it more or less makes you a galaxy brain. I know that I used to study IQ tests and I think that might have contributed to my current success.

This works and is extremely easy to market, because insecurity about one's intelligence is a very common, and easily accessed pain point. Its one of the few things that I always make sale from when I post about it somewhere.

What niche would you be targeting with this? And how would these be different from online brain puzzles people can find for free?

It does not solves a problem so finding profitability will be very hard