You can get a some information on system requirements here
. They have released system requirements for Windows only, sadly enough.
And no, no 64 bit version, multilib is needed. So Trine 2's Linux version is a no-go for me, my 32 bit systems can't handle it and I don't want to install multilib on my main machine just for one game.
May be I will have a look at the Windows version later on.