MONEY
Money and time are the criteria in development. With enough money and enough time, one can do anything.
RISK
In life, lots can go wrong. Which is why development is so risky.
CHARACTER
The key to development is the character and drive of the developer. Can he overcome the many challenges that present themselves. Can he stay true to the designs. Can he complete the work. How will it be received? Drawings on paper are one thing, development is another.