Detect the appropriate language per region and start the demo but provide a pointer immediately within the demo to change it if necessary.

If you do a video on the landing page, have it play automatically (could be a high res playable gif).

If mic access is not needed for all the games (wait, there's games and there are multiple of them?) then sure, default to a non-mic game if it still provides value. I've only looked above the fold, but it seems like a complex product offering. Below the fold, its very wordy and still not explaining much how it works. The 'Milestones' part is taking too much space. Kick it out to an About page or something. Probably the same with your 'Story'.

Good luck!