Jeremy is looking for a challenging gift for his 7-year-old kid, living in the UK, that he can play with him online. Leo says that there's a fun networking puzzle computer game that you can play with your kids, called Factorio. It requires cooperation, and you can communicate via Discord. That could be a fun but challenging game. Brilliant is another one, but that's a bit mature for a 7-year-old. Probably better for middle school ages. There are also Words with Friends and Animal Crossing.
Minecraft is ideal for a kid his age as well, and you can run a server on a small computer like a raspberry pi. Check out the book Learn to Program with Minecraft: Transform Your World with the Power of Python by Craig Richardson. It not only teaches you to program using Python, but it comes with software for a Minecraft Server. This could be the perfect thing to experience together online.