[LabMechanic]

My personal suggestion:

Make sure you are able to set pixels and create audio samples (sine function sampled over a discrete time steps). Also make sure to store the results as PPM P3 (very simple text-based image format) and WAV. Some inspiration form Wellons: https://nullprogram.com/blog/2017/11/03/

Then you can implement a ray tracer, a rasterizer or audio generator.

Other ideas:

  - implement your simple neural network learning XOR
  - implement your hash table or your version of std::unordered_map (array + 
    hash function + tombstones)
  - arena allocator
  - dynamic array or your version of std::vector
  - a circular/ring buffer (that you can also use as a queue/stack)