I don’t know much about other game designers, and I am sure this is nowhere near as complicated or time-consuming than more simple game designs or genres. However, I just wanted to tell everyone how long it has taken me so far to get where I am.
Where am I? As completed with the game design as I can be, before beginning production. 90% completed with a lot of the graphics. >0% completed with the Unity3D scripting, programming, and game production.
I have, however, read many threads on people who want to make MMORPG’s (perhaps the most complex game possible) and having been working on this for over a year, I have tried to do the following
Goal: Spend as little money as possible.
Result: I have spent over $3000 already, and still have to spend more. I expect a minimum of $5000 before I even begin the game’s first stage (a final, polished state of a prototype of a very small version of only a few features).
Goal: Focus on programming and creating the game itself.
Result: After over a year, >0% has been on this, while the first 12 months were focused on game design and asset research and the last 4 months were only creating the graphics, models, animations, and contracting the work out to other individuals.
Goal: Make this my full time job.
Result: For the most part, this has been my full time job. As a result of being forced to create or buy the majority of my own assets, I landed a contract job redoing a different MMORPG’s graphics. This was done to help FUND my own game. The result was landing a PERMANENT job in the MMORPG company (part time) to continue to help fund my own MMORPG.
Goal: Finish production within 6-8 years.
Result: Very very fast production. The actual project started in November, although I dabbled and began learning Game Graphics 2 months prior. I actually figured the graphics would take me, by myself, 1 year to complete. Instead, it only took about 5 months (this includes learning and my estimated remaining time working on them). I expect to get a working a small demo of the combat system (only) with nearly 0 features by the end of March (2011). I hope and see a realistic goal of 2 years minimum development, 4 years maximum. Actual length of the MMORPG project entirely depends on player popularity. If the game is not fun or successful in ANY way (>100 players) the project will end as a small multiplayer arcade game.
Goal: Learn to Program with 1 years worth of experience.
Result: Learned to 3D Model, texture, animate, shader, and lighting Game Graphics with 4-5 months of experience.
New Goal: Do all the Graphics myself.
Result: Too difficult for me. Have to hire others to help, and pay more out of the game’s budget.
And last but not least…
I have been designing the same game, with the same handful of features— for over a year now, nearly 18 hours a day. I eat, drink, sleep, and even POOP game design on this sole project. I have went over so many hours of so many features, I re-create the same ones I invented 1 month ago, because I lost the note and was overwhelmed.
I have scores of full notebooks written and drawn on, and for my Birthday my wife bought me 10 more notebooks-- most of which I have used (and that was in October).
This is over 4000 hours spent on designing one game, and only a handful of features. Although these features are complex. Over 500 of these hours have been spent in discussion, debate, and research with other programmers, artists, and players. I have done multiple versions of surveys for the same feature (Playable Races) because of the ever-changing paradigm of game design and what the players want.
This may be my own fault for having such a robust game, taking on challenges others would ignore, or most of all: being involved with the community, without sacrificing my game design. Asking and following what Players want-- without changing my goals or game design core. This is a challenge in itself to “Stick to your guns” but if the ideas are good, players will naturally like them, and they will only require ADJUSTING not completely changing, although some features may need to die, as long as they don’t severely impact the rest of the game design.
I just thought I’d tell others what they might expect if they want to seriously make a MMORPG. At least from my world, having to learn everything from the start, having only (over a) decade of MMO gaming experience (which often encompassed 18 hours a day gametime for several years), gaming my entire life in ALL genres, creating PnP games even as a teenager and an adult, and being extremely dedicated (and nearly obsessed) with game design itself, in all genres (I love all genres, not a single one do I dislike, and I could tell you genres you probably dont know about).
It takes a lot to make a MMORPG, and this is coming from a person that hasn’t even begun what is the most difficult task of all: balancing the game design (players, characters, combat systems, etc.) and core engine design (Unity3D scripting C# programming, as well as Server architecture and Intensive Networking)
If you’re not willing to commit to several years, thousands of dollars, and a minimum of 4000 hours of your life thinking of every possible outcome, failure, and flaw of each of your features— it may not be the genre for you. That is, if you want to cover all your bases anyway 
It would be much more simple making a very basic MMORPG with @ symbol graphics, supporting only a handful of players in a turn based environment! 
Also, you need to be confident in your core game design to compensate for any feature to be cut. Because honestly… the game will look nothing like it originally was before you started. And then it will transform back into what you originally had planned. Without anything actually changing. (Basically, you don’t know what will happen). Features will be cut, Features will be added, and it is a headache to keep the core design (what the game is all about) stable while doing either of the above.