The game I play is seeing how much marginally useful crap I can shove onto a single site and still make money. There's no shortage of free information available in bulk that just needs a home with ads. Every once in awhile I'll tweak things with AdSense to try to increase revenue but generally my business plan is to just add more information to my sites.
I think if you do it for money then it's a job. If you do it just as a hobby (adsense is just a side income) then it's your favorite pastime although it is pretty addictive!
I used to be addicted to the World of Warcraft in my spare time, now I'm addicted to checking my AdSense stats like crazy and tweaking things. It's definately a game of sorts to see how much money you can make in a day compared to the past and it's especially fun when you have multiple revenue streams and tons of sites to tweak on.
Adsense makes up about 15% of my total daily income. I don't have time to "play" with it. Much more important things to do elsewhere.
It is definitely a game for me I have a very well paid job in the “real world†as a Technical Manager. Even if could raise my income to the same level or more as my paycheck I would never base my income on the money from Adsense. I use around 6-10 hours a week working on my projects and I make mid x.xxx$ month. /askhoej