gamessoftware-recommendation
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What games are available that run natively on Ubuntu?
Please limit one game per answer – and include why you enjoy the game.
Déjà Dup is (from Ubuntu 11.10) installed by default. It is a GNOME tool intended for the casual Desktop user that aims to be a "simple backup tool that hides the complexity of doing backups the Right Way".
It is a front end to duplicity that performs incremental backups, where only changes since the prior backup was made are stored. It has options for encrypted and automated backups. It can backup to local folders, Amazon S3, or any server to which Nautilus can connect.
Integration with Nautilus is superb, allowing for the restoration of files deleted from a directory and for the restoration of an old version of an individual file.
Note that as of February 2016 this project appears to be almost completely ignoring bug reports with only minor triage activity and the last bugfix dates back to 2014, though there are new releases with minor changes.
Category: Other
StackApplet is a GNOME panel applet that monitors your activity on any StackExchange site.
stackapplet 
in Ubuntu Software Center
Get the latest version as follows:
sudo add-apt-repository ppa:stackapplet-dev/stackapplet
sudo apt-get update
sudo apt-get install stackapplet
The first time the application is used, run
python /usr/share/stackapplet/stackapplet.py &
from a terminal.
Best Answer
World of Goo
An excellent puzzle game that runs natively on linux, DRM and region free.
It's $20, but there is a free demo available to see if you like it. If you do like it, note that it's developed by a small independent studio who trusts you enough to keep it DRM-free, so please buy it and your $ will be going to the right place!