Hey I had written up a game design draft for a bird game like 10-15 years ago! It's sad we still don't have one.
Mine was open world with a small coastal town, you'd be able to fly pretty much everywhere and as you progress through the story mode (which was basically a small number of objectives really) the other birds you meet would be unlocked with their own little story modes.
Being a coastal town you start as a seagull, so the game had the working title of "Seagull game".
This kinda makes me want to look back into game design again, it was a path I never seriously looked into, despite writing a few design docs back then (none of those ideas have ever turned into games afaik).
A bird simulator? Check out this Red Dead Redemption 2 mod!
Edit: Be careful because there maybe location spoilers.
That bird animation is goddamn beautiful. Look at the hawk's feathers in the wind.
The notes on the video mention they just did some model swapping... does that mean the game already has set controls for birds? Were they planning another peyote deal?
This just makes me sad now.