It is my belief (based upon my own experience, observation of others and reading of other folks' blogs) that many gamers seem to go through certain similar stages in their life in regards to what and how they play. I realize this isn't universal to everyone and the specifics vary from person to person. Even so, I've seen enough to think that I am on to something here. Below I will list what I consider the different stages in a gamer's life.
This represents a Gamer's introduction into the hobby. It typically begins with hearing about a game—usually through a slightly older acquaintance or relative. In my case, I remember older cousins and their friends talking about gaming. This got me curious. I bought my first game (or rather, my parents bought it for me). This was Basic D&D. I had absolutely no idea what I was doing, but I loved it anyway. Many abortive and shallow attempts were made at running games and even campaigns without having any idea of how to go about it. In my case, living in South Dakota, there were very few peers or mentors I could turn to so I had to muddle through this learning stage myself.
Growing up a little and building on the experience of those wild and wooly days of learning through doing, a Gamer begins to feel a sense of 'maturity'. They know the rules and are now running at least semi-successful sessions or even campaigns. This is typically in one (or maybe two) primary game systems. The gamer begins to feel that they are a 'real' player (or GM) now. Along with this sense of maturity comes a kind of brand loyalty. The games you are playing become YOUR games. You buy 'official' material for those games and often follow doggedly along with whatever expansions and changes are made in the official rules. Why? Well, because they're OFFICIAL of course! A gaming company made all these rules, so surely they made certain everything worked well before introducing it to the general public. This was certainly my attitude with D&D. I progressed from B/X to AD&D and incorporated all the rules from Unearthed Arcana without any thought as to 'game balance'. This is the phase where house-rules are often implemented, but I don't think most gamers drastically alter the shape of the systems they play.
Feeling secure in their primary systems, Gamers begin to experiment with more and more systems and settings. Sometimes, this means they even switch their 'primary' system to something else they like more. When I was growing up, there were a slew of different games, and every one of them had a different system associated with it. Though some game companies made attempts at creating an overarching system to handle different genres (GURPS, GDW, etc.), most everything was unique. So if you wanted to play one genre, you learned one game system. Another genre and you learn another. For me, this phase led to my experimenting with Star Wars D6- which became my primary system. Even so, I dabbled in all sorts of other games: Battletech, HeroSystem, Dark Conspiracy (GDW), Mythus/Dangerous Journeys, Shadowrun, Rifts, etc. etc. Even with all the experimentation, gamers at this stage tend not to bend the rules too far. House rules are again normal, but systems remain basically unchanged.
For one reason or another, many gamers eventually reach a point where they simply stop gaming. For most this is due to real life. You graduate college. You get a job, a family, responsibilities. You don't have the time, even if you DO look back fondly on your gaming days. Alas, for many gamers, this seems like it could be the FINAL stage in their gaming life cycle. They come to regard games as 'immature' and move on. Others retain a peripheral awareness and remembrance of gaming, but actually play very rarely. When they do it is usually in their favored systems—with all the experimental stuff having fallen by the wayside.
At some point, some gamers will have a sudden resurgence in interest of their hobby. In many cases it may just stem from simple nostalgia. But whatever the reason they begin to look through their old books and materials. They begin to remember the fun and wonder if it could ever be like that again. This renewed interest has (in recent years at least) been helped along by the internet. Here you can not only find a lot of information about gaming of the past and present, you can also read about and even interact with other gamers- many of whom might also be in the same rediscovery boat.
Recreation and Re-creation
At this point, a gamer starts to make gaming a part of his (or her) life again. There is a sense that all the fun they remember CAN be found again- that games don't simply stop being fun once you reach a specific age. For many gamers, however, there comes (along with their maturity) a greater sense of ownership of a game. They aren't looking just to follow 'official' rules or play 'official' adventures. They feel they can put their own spin on things—moreso than just house rules. This leads to a lot of players tinkering with new game designs or overhauls of their 'go to' systems. Likewise, many feel confident enough now to produce their own original adventures and even sell them to other gamers. And for their part, the consumers of these games feel quite free to put their own spin on things. Of course, not all gamers 'reinvent the wheel'. In fact, a lot return to their roots- even 'abandoning' their former go-to systems in favor of the simplicity of earlier iterations. But in my opinion, this too just shows a willingness not to accept someone else's concept of a game in favor of what works best for them- even if that design is considered 'obsolete'.
I suppose after rediscovering gaming, a gamer could once again allow it to fall from their life, but I know that a lot of people see themselves gaming for the rest of their lives. It is a social hobby that can easily be shared with family and friends for.. well. Forever actually.
I don't think I'm just speaking for my own 'generation' of gamers on this, either. In interacting with younger gamers, I see a lot of the same practices and prejudices that I went through—The Dogged Loyalty and Experimentation stages especially. Which makes me wonder if, some years from now, we're going to see an 'old school renaissance' of 4th Edition d20 and other contemporary systems? I'm betting we will.