Ask HN: Do you have a challenging C++ project ideas to build out?

I’m looking for an idea I can finish in a reasonable amount of time (1-2 months) Whenever I’ve had to think about project ideas, it’s always been about a website/web application of some kind. However, I’ve been branching out lately and I’ve learned a lot about c++ and built quite a few small projects (CLI mainly) to demonstrate what I learned with great success.

Now I feel ready to try something more challenging and multi tiered in complexity, something I can show off on GitHub. The problem is that I don’t know what to build, do you have any ideas?