So I'm on Ubuntu 14.04 and I was getting the following error when I try to run the game with ./start.sh:
./PapersPlease: No such file or directory
I looked at the system requirements and I saw that there were some required packages. So I went to install those, but now this is the error:

Error : Null Function Pointer

Does anyone know what might be going on?

Have you installed it with the deb installer or the tarball?
I've checked the start script from the tarball and it seems okay.

This is with the tarball, but I've tried both and neither work

Try this:

sudo apt-get install libgl1-mesa-glx:i386

or this:

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/lib/i386-linux-gnu/mesa