Fun little find I made while looking for a Banjo Tooie wallpaper.
It's some sort of early French videogame wallpaper site. As mentioned above, they just rehost official 2000's era wallpapers with their logo plastered in the corner. It's a real' pain to get it to load dates past 2002 on Wayback Machine, at a certain point they must have stopped paying the domain registrar since past that date the site is just a "Freenauts" error screen, but if you pry at a few links you'll eventually find a way to some later dates.
It's a cute little website, I don't speak a lick of French but my favorite translated line is "-some images being 'progressive'-"
https://web.archive.org/web/20010619202949/http://ecranjeux.free.fr/
interesting page, thanks for sharing
how sad the Sonic ones return 404 =(
Don't worry! It's likely the Sonic wallpapers on ecranjeux were just the 1280x1024 versions of the SA1 wallpapers archived here!
There is a small chance that they hosted some SA2 wallpapers as well, but the game would have only just released at the time. It's unlikely that there were official wallpapers out at that time.
I tried to find where they were hosted on SEGA.com in 2001, but it seems SEGA's site was unusually secure for the era and it made archiving anything impossible, all the links redirect to a 2011 error page.