gamespackage-managementsoftware-center
Well, I want to install the two EA games that arrived in the software Center recently. But these packages seem to be missing as in the following picture:
I've tried to update the sources, and tried to search manually but no luck . And I've tried installing them using the terminal also.
Despite the fact that they are online games, how can I fix this?
I am on Ubuntu 12.04.
sudo apt-get clean
cd /var/lib/apt
sudo mv lists lists.old
sudo mkdir -p lists/partial
sudo apt-get clean
sudo apt-get update
Update: This might not help in some later versions, which might require alternative solutions like the one in the other answer, or this one that seems to do the job in some cases under Ubuntu 16.04:
sudo apt-get update
sudo apt-get dist-upgrade
It boils down to an issue between the apt and snap versions of Ubuntu Software.
This answer from an earlier question helped to provide a solution.
What I did
In terminal:
snap remove snap-store
sudo apt-get install gnome-software
followed by
sudo apt install gnome-software-plugin-snap
That installed Software 
as opposed to the large yellow icon previously associated with Ubuntu Software after which the "missing" packages were then correctly listed.
There are solutions to restore the old icon if I wish (not essential) and to reinstall snap-store which can apparently co-exist with the apt version
Best Answer
While you can still play the games (as OrangeTux pointed out), it would be ideal to install these through the Software Center, so that EA can see the strength of the Ubuntu platform.
For now, that seems to be impossible for many users, but you can subscribe to the bug report on Launchpad.