Solved: Now you can run Amnesia even on computers which do not have external graphics card and have only Intel HD graphics card!
Why? Amnesia needs S3TC support which the open source drivers that come with the OS do not support.
Installing libtxc-dxtn-s2tc0 solves it!
The solution is very simple.
Method 1 :
Copy and paste the following command
sudo apt-get install libtxc-dxtn-s2tc0
Method 2 : The Hard Way
First go to "Software Center".
Now search for libtxc.
Among the results install "Texture compression library for Mesa".
Now run Amnesia. Set all graphics settings to low just to be sure. You can experiment with higher settings later.