What was the first PC game which really grabbed your obsession? Counter Strike? Command & Conquer? Quake? In my case, I must sheepishly admit it goes back much farther than that.

Wolfenstein 3D was my first truly compulsive gaming experience – sneaky sessions on the office 486SX during lunch breaks. I’m not really that old – I started work when I was five. Honest.

It was obvious even then that PC gaming had huge potential – and huge potential to take over your life. The PC games industry has made huge leaps forward in the intervening decade and a half. It now points the way forward for entertainment in general, in particular the idea of paying monthly for an ever-evolving game experience.

The billion dollar question

Wolfenstein 3D was shareware. Its success propelled its creattors, id Software, into the game-developing big time, and the chance to sell bucket-loads of retail-boxed games. But in a recent report, the NPD Group calculates that the online subscription market for PC games has just topped $1 billion, surpassing retail PC games, which have been declining.

Only a few years ago, the online gaming business was worth a third of what it is now. Back in mid-2004, the Yankee Group estimated the annual value at $352 million, but predicted that online games would hit $1.1 billion by 2008 – which has proven to be absolutely spot on, looking at the NPD figures.

Where once it was sneaked FPS sessions during work breaks, now the majority of PC gaming income is derived from all-night sessions on a Massively Multiplayer Online Roll-Playing Game (MMORPG).

The top entry on the NPD list will surprise nobody - World of Warcraft. Try playing that during your work lunch break and you would soon be out of a job. And a girlfriend. And your ‘real life’ friends...

Apparently, there are 11 million monthly game subscribers. This actually isn’t that many when you consider there are now around 1.5 billion people worldwide using the Internet. So online interactive entertainment clearly has a huge growth potential ahead of it.

Being social makes all the difference

It became blindingly obvious when the first network-capable games arrived, like Doom II, that this was a very different gameplay to single-player.

Sure, you can discuss strategy with friends, but the post-game punditry of a good network deathmatch is on a different level. Then, as the first MMORPGs came out, such as Ultima Online, their arrival felt more like a networked version of very niche activities like Dungeons & Dragons.

But the social element of online play was also there, and in fact games like World of Warcraft and Lord of the Rings Online are proving very big business indeed – much bigger than their paper-and-funny-sided-dice predecessors.

Dungeons & Dragons, for example, is estimated to have made a $1 billion in its entire 30-year lifespan. Ironically (or maybe not), the fourth Edition of the RPG is due June 6, and will rely heavily on online resources such as D&D Insider.

The amazing thing is that PC gaming is not the biggest chunk of the gaming business – that is clearly consoles - GTA IV has already made $500 million on its own. Consoles are still undergoing the online hookup, but even more potential is available there. The Wii version of the BBC iPlayer is just the beginning. Wii Fit classes online, anyone? Maybe not, but you get the general idea.

Games like World of Warcraft have made the online subscription business bigger than retail PC gaming