Let's say you had a group of a few people, you, and 9 other people. How long would it take to make a game like Farmville for both Android and iPhone?
It depends on your experiences. If all of the team are experienced this type of game and mobile platform, it may take 6~18 months.
[FONT=Verdana, serif]I would say months. If you want to make your game a commercial success, even more. Like iamagame said, it depends on your experience. If you want to have a better idea, I suggest that you make a very functional prototype of the game you are planning. I often notice when programming that many problems appear and they didn't seem obvious at the beginning. It's very hard to plan everything unless you are a veteran. You can also do research on the Internet about similar games to find the developer's story. Quite often, you'll find the developer talking about the time it took, pros and cons, and more. That provides valuable information to know before undertaking a project too big and realizing in the middle of the road that the destination is many times farther than we thought.[/FONT]
It depends on the platform specifically, but it can take some time and will be harder than you might think. But it definitely depends on your experience level as well. One thing is for sure about the development time: whatever you think is a reasonable length of time to spend on the game, double it. Things will come up, things will go wrong, and You'll discover things in your game you never even knew about in the beginning. And like Gaia said above me, research what others have already done, and don't just focus on the good stuff, listen to their personal low points as well. It's not all going to be cake. Either way, good luck!
Say that you already know unity and is pretty good at coding and things like that, switching over to mobile wouldn't be that hard, but making a game still takes a lot of time.
It really depends on the type of game you are making. I mean you could make flappy bird in less than a day with a full team. There are plenty of people that do hack-a-thons and make games in less than 24hours. So you need to look at the scope of the project you are trying to accomplish with the resources you have at your disposal and you should be able to arrive at a decent time frame.