Counter Strike Offensive gives you the nostalgic feeling and the original version of the Counterstrike game that was made as early as the year 2000. You should download this game today to get the ultimate experience that you have always wanted! You can discover the same original maps, weapons and also characters if you like to, but with improvements.
You can download the CS:CO mod on a lot of different sites on the web. For instance, you can visit the likes of moddb and choosing the latest patch which will be on top of the site. All you need to do is to extract the file and you will get a folder on your computer that will be called CSCO.
How to launch CS: CO on Steam
From here, you need to open your program files and find the folder named steamapps\sourcemods. After that, you will need to drag the CSCO folder into the sourcemods folder. When you have done this, you can restart Steam and you will be able to play Counterstrike Classic Offensive, which will be available for you in the game library.
Counterstrike Classic Offensive is also available for you to play online. The only thing you would need here is to find a server you want to play on. You can easily launch a server IP in the CS: CO console if you want to play with your friends. One of you will be the host and the others will play on that given server. There are official servers out there too.