We lack experience with game development.
We lack necessary skills in machine learning.
We lack experience with graphics.
Communication is always an issue for large projects.
The integration of components could cause problems if we are not proactive in avoiding such problems.
We lack management leadership (in team software development).
Coding styles may clash. All members of the development team need to be able to understand one another's code. We must be conscious of this as we construct our code so as to make it as clear and concise as possible.
None of us have had significant experience with C# and the .NET framework.
Our product could be uninteresting if we scale back the project too much.
The scope of the project could be overwhelming if we add too many features.