Yesterday I was facing the same problem and found the answer in this thread.
So, you have to install the missing 32-bit libraries in the following way:
sudo apt-get install package-name:i386
For me the required packages were:
libopenal1:i386
libportaudio2:i386
libglu1-mesa:i386
libvorbisfile3:i386
libgtk2.0-0:i386
I installed them step by step and checked the still missing libraries after each package by entering following commands in the Trine 2 install directory (the first one is enough only once):
export LD_LIBRARY_PATH=./lib/lib32
ldd bin/trine2_linux_32bit | grep "not found"
ldd bin/trine2_linux_launcher_32bit | grep "not found"
If further not found libraries remain after installing these five packages, please check the above thread how to find out the package name of a library.