If you aren't aware, prior to the sound era (1929) at least 70% of films are lost to history. Some are completely lost, some are partially lost. The extent of this is, if you're interested in any singular film movement, director, actor, writer, chances are you will find SOMETHING of their career that just doesn't exist anymore.
Now I COULD link the wikipedia page here (in fact, I just did) but I wanted to dedicate a page to lost cinema I've collected over the years and "I want to see it."
(I have no idea what this is from)
Sometimes all that survives of some films are the trailers
I found this online and is technically the first Picnic At Hanging Rock adaptation. It was a project made by a 13 year old film student, left unfinished because Peter Weir got the rights for when he made the '75 film. I find this version interesting. I don't think it would've been better than the first film we got (the 2018 miniseries...very possible!) but I do find it unfair I can't find this version ANYWHERE online!