I'm working on a paragliding track visualizer: https://skyviz.io - I started it just for myself, then it kind of got out of control, and now I'm spending wayyy to much time on it
After many years of working on enterprise crud apps, it's so refreshing to actually use some maths and 3d programming again :D
But now it seems the the only way forward to make more out of the product is by doing marketing... Something that is absolutely NOT my area of expertise nor interest