[potatolicious]

Counter-Strike had a similar effect on me. I'd be coding since long before CS, but most were small, simple hacks.

Seeing the success of Counter-Strike, and the mod-mania of that era, got me interested in modding, where I was first exposed to the complexities (and math!) that "real" software entailed.

From there I went on to write some standalone, small games, then went deeper down the C++ rabbit hole which helped me get my first software internship. The rest is, as they say, history.

[freehunter]

I got started at 15 working with teams to make CS hacks harder to detect. I now work in netsec doing packet analysis to identify new malware via network signatures. It's funny how script kiddies, given proper motivation, can grow into professionals doing real work. How many thousands (millions?) of our fellow IT workers can trace the direct roots of their profession to video games they played as kids?

[cgag]

Writing scripts and bots to cheat at runescape in middle school for me.

[trafficlight]

I remember trying out tons of mods for Half Life and Quake around '99-2000. That's all but disappeared now.

Are there still active modscenes for newer games? Minecraft is the only one that really comes to mind.

[potatolicious]

Nothing has been as easily moddable as Half-Life, with the same install-base.

I suspect there's another problem with mods today: asset production. In Half-Life's day even I could hack out a semi-passable player model in a day or two. Nowadays, producing assets for games has been made dramatically more complex. In short, you really can't find a lot of people willing to produce that quality and complexity of art for free. The size of teams required to put anything together, as a result of this, has also put a lot of things beyond a mod team's modest reaches.

I think that's why a lot of the indie excitement is around casual and "low-fi" games like Minecraft. Assets have always been a major blocker, and when you embrace the fact that you're not AAA, you have a better experience with it.

[estel]

Some games, yes. Epic foster an incredible community with their incredibly generous terms for licensing the UDK out to all. Skyrim will no doubt see a profusion of mods; the Total War games all have a healthy modding community; all Valve games are as moddable as HL2 was, given they... uhh... are still on the same engine.

[patricklynch]

There seem to be a lot of new Skyrim mods coming out every other day. Mostly cosmetic stuff, but I wouldn't be surprised to see more 'total conversion' style work soon.

I haven't really checked moddb.com since Unreal Tournament 2004 was the big online game, but it seems to be going strong.

[T-hawk]

Different genre and a few years old now, but Civilization 4 is supremely moddable with a very active community. Firaxis released the entire source code to the game rules engine!

[v21]

There's a whole world to discover: http://www.moddb.com/mods

[ordinary]

Bethesda games tend to be very moddable.