I wonder how long it will take a single person to write a complete MMO engine. Is this possible? This question is only about the engine development. There will not be a lot of models or level design or quest design. I want to use C++ and OpenGL but no other framework.
Eh, this question isn't really a good fit for the site but since i spent some time researching a very similar question, I figure I'll post what I determined.
The main problem I have found with developing a large scale game solo is the time it takes. If you wanted this as a hobby and expected it to take a very, very long time, then yes it is possible.
Another problem with doing something solo is that you cannot find all the answers you are looking for online. Working with a team of programmers is invaluable because if you are having a hard time determining how to do something, you can have other people familiar with the code take a look and give their input.
It is really difficult to ask anonymous people online these questions because you can't (or won't) give them all of your code and when people don't fully understand, they probably wont respond.
So now, if you are a highly experienced C++ OpenGL programmer, you might already have some code that you can use or know how to set it up. That is great but it all depends on how much time you can dedicate and how determined you are with completing the game. If you are new to C++ and OpenGL, it makes things a lot more difficult because when you say 'engine', do you really know what that all encompasses? There are a ton of things to take into account and having others be able to have input reduces the odds of you forgetting something or implementing it wrong.
It takes teams of programmers potentially several years to complete a game, so you should expect to spend a multiple of that time working on yours. Its a very difficult task and while i don't discourage you to try, just be aware that it is a pretty much uphill battle the whole way.
I only say this because I have attempted this before and got discouraged and moved on, after much frustration and lost time.