I'm happy to announce that the first version is available since May! You can play Qwixx here: https://qwixx.jboisseur.xyz
I've been working on this project for a long time. It started when I took a few Python lessons a few years ago but I abandonned because I had no clue about how to get an UI. Going back to HTML/CSS and then starting learning JavaScript put me back on tracks.
So many things! Particularly in JavaScript where I worked with arrays, listened for events, ran a huge amount of loops, created functions, toggled CSS classes, saved data in the user's browser etc. I also learned about debugging and using the web developer tools on the browser. I had to use some PHP as well, for saving best scores.
This said, I think the biggest take away was to divide the work into achievable challenges and push the harder ones at the end. Keeping this goal in mind: at the end of each step, the full game should be playable. This way, the path was most of the time enjoyable, and having something to share along the way is very rewarding.
I already started working on version 2, which is about allowing two persons to play on a same device. I'm experimenting working on cold and old code. It's very time-consuming but I try to refrain from starting all over on a blank project. I try to improve what's already there and implement what's missing to achieve this 2-players goal. One small step at a time.