If you are a CS fan,you may want to play CS in ubuntu if you also enjoy operating in ubuntu.This tutorial will tell you how to install Counter Strike on ubuntu.
1)First,you need to install wine by Add/Remove Applications (Applications–>Add/Remove…) and type wine in search field to find it.or you can get it from following link for free:

http://www.winehq.org/

Another way,command line for installing wine:

1.Add the repository’s key to your system’s list of apt keys by copy following to a terminal window(Applications–>Accessories–>Terminal)

wget -q http://wine.budgetdedicated.com/apt/387EE263.gpg -O- | sudo apt-key add -

2.then,add the repository:

For ubuntu 9.04

sudo wget http://wine.budgetdedicated.com/apt/sources.list.d/jaunty.list -O /etc/apt/sources.list.d/winehq.list

For ubuntu 8.10

sudo wget http://wine.budgetdedicated.com/apt/sources.list.d/intrepid.list -O /etc/apt/sources.list.d/winehq.list

For ubuntu 8.04

sudo wget http://wine.budgetdedicated.com/apt/sources.list.d/hardy.list -O /etc/apt/sources.list.d/winehq.list

3.at last execute following command:

sudo apt-get update

sudo apt-get install wine

winecfg

the last command will create .wine file folder and go to wine configuration.

2)After wine installed,download Tahoma.ttf from here:http://www.webpagepublicity.com/free-fonts/t/Tahoma.ttf

then,in a terminal window locate to the file and execute following command :

cp Tahoma.ttf /home/user-name/.wine/drive_c/windows/Fonts

where “user-name” is your ubuntu user name.

3)Download steaminstall.exe:http://halflife2.filefront.com/files/Half-Life/Official_Releases/Steam%3B2934,install it by command:

wine steaminstall.exe

type the file name you downloaded instead of “steaminstall.exe”

4)Type following to launch steam:

WINEDEBUG="fixme-all" wine steam.exe

Tips:
You can also install and play CS with PlayOnLinux(GUI tool) in Ubuntu Linux