I randomly visited https://logicmastersindia.com/?g=links and found out that some links there are outdated and don't work any more.
I can't say the correct new addresses for all websites there, but for Russian Puzzle club the right link is http://diogen.info/ (and the site doesn't have any online competitions currently). You can also add link to http://www.puzzleduel.club/ if you want.

If the page with links to other sites is outdated, it can negatively impact user experience and your site's SEO. Outdated links may lead to broken pages or irrelevant content, frustrating visitors and reducing credibility. Regularly review and update such pages to ensure all links are active, relevant, and add value to your audience. Consider removing low-quality or irrelevant links and replacing them with up-to-date, high-authority sources to maintain your site's relevance and trustworthiness.