Just had the same problem with Rayman 3 not launching on Windows 10 AU x64.
Problem fixed by installing Microsoft's (legacy) DirectPlay library.
You can do that via Windows: "Programs and Features" >> "Turn Windows features on or off" >> "Legacy Components" >> "DirectPlay".
Game runs without any problems after doing this.
I can confirm this works at least on Windows 10 64bit Home (Creators Update installed).
After some messing about, it works for me on Windows 10 x64
I'm trying to play the Hebrew version. I still own the original box and discs I bought back in 2004 or so. I installed the game but it won't start (it launches an unkillable "Rayman3.exe" process that stays running in Task Manager until I restart my computer). I purchased GOG's English version and it works like a charm, so I was hoping I could also fix my Hebrew version.
I completely removed the game and also removed Better Rayman 3 (which starts a "BR3_Config.exe" process and immediately kills it, but no window appeares).
I enabled the legacy component DirectPlay
using the above method, then installed Rayman 3 in "C:\Games\Rayman 3 (hebrew)".
I also installed DirectX8
(even though I obviously have DirectX12 already) when the installer asked me to.
In an earlier time (before I uninstalled the game) I tried editing the ubi.ini file but it didn't solve my problem, so I just left it the way I edited it (so now it is different than the default file the installer creates - I attached its contents below).
I created the folder "Ubisoft" in %appdata%, and copied the edited "ubi.ini" file from C:\Windows\Ubisoft into it.
I set "Rayman3.exe" to run in compatibility mode in Windows XP SP3 and as an administrator.
Then I launched it and it opened a 1280x960 window in which the game was running smoothly!
Now I'll try my best with Better Rayman 3 to try and get 1080p fullscreen. But I'm happy that it finally works! Contents of my edited "ubi.ini" file
(notice that the language is still "English" for some reason:
Gli_Mode=1 - 1280 x 960 x 32