Well there is a Chinese Drama "Love O2O". Both, the ML and FL are part of the CS department.
*Edit : You must've probably watched "Strong Woman Do Bong Soon". The ML is the CEO of a Game Company.
City Hunter : The ML works as a part of the IT department in the Blue House in disguise. Well he does hacking too.
Memories Of Alhambra : Literally based on an AR Game.
Also, someone has already mentioned "Search : WWW" . It's a really great watch. Apart from everything in the kdrama revolving around search engine, the ML works as a music director for games too.