Is Minecraft Let's play a solution?

This year I'm gonna be taking the Proficiency exam and hopefully get the certificate. I always wanted to improve my speaking skills in a way that I'm not very shy and clumsy.

So, lately I was thinking of starting a Let's play series with my microphone just to practice a bit, and I thought of Minecraft (because I'm an expert on it) however there are tons of other commentators. Is it worth it or I should select something else?

Hmm good question.
If you know a lot about minecraft and are comfortable, then go for it! Your speaking skills are often better if you talk about a subject you enjoy. There are a lot of other people, so your videos will need to stand out in some way. Make some jokes and be light-hearted about it. Tell your friends to watch them and give feedback before you post your videos.