UPDATE: loading wasn't successful

When I type sudo ./witcher.sh , I receive

Verifying archive integrity... All good.
Uncompressing The Witcher 2: Assassins Of Kings - Enhanced Edition 100%
Collecting info for this system...
Operating system: linux
CPU Arch: x86_64
trying mojosetup in bin/linux/x86_64
USING en_US

PANIC
Initial setup failed. Cannot continue.

Error: Couldn't run mojosetup

*.sh is set as executable
md5sum: 56a81ffa7156909bf96b4663120a5c88

You may have a corrupted download. My md5sum for this game is:

3fff5123677a7be2023ecdb6af3b82b6

And it installs and plays correctly on LinuxMint 18.1 Cinnamon 64bit.

I'd also suggest that you do not need to issue the sudo command to install the game. Only for installing the dependencies.