Saving and sharing work
There are two types of project your work can be saved to. These do not affect the functionality of the game at all, but have different advantages and disadvantages during editing. One of the types must be chosen when creating a new project.
Projects can be saved to a folder. This stores different parts of the project in different files. For example, each layout is saved to a separate file in a Layouts subfolder.
Folder projects save and load quickly. This makes them more suitable for medium or large projects.
Folder projects are good for collaborating within a team, since it is easy for different people to work on the different project files and later merge them. See the section on collaboration below for more information.
The main project file in a folder project has the extension .caproj. Note this does not contain the entire project: it is simply a list of other files used in the project. If you want to share a project, the .caproj file is useless on its own - save to a single-file project (.capx) instead.
Single-file projects (.capx files)
Projects saved to a single file are often more convenient for small projects. There is only one file to send, upload or share. However, they save and load more slowly due to Construct 2 having to pack and unpack the project from one file. They also make collaboration more difficult than if the project is saved as a folder.
.capx files are simply a ZIP of a project folder. You can rename a .capx file to .zip and see the project files.
Converting between types
It's easy to convert a single-file project to a folder project and vice versa inside Construct 2. Simply open a project and choose File - Save As Project... to save it to a folder project, or File - Save As Single File... to save it to a single-file project.
Since .capx files are a ZIP of the project folder, they can also be converted to a folder project by renaming them to .zip and extracting the folder project contained within. Similarly a folder project can be converted to a .capx file by compressing it to a .zip file and changing the file extension to .capx.
Collaborating on projects
Construct 2 does not contain any of its own collaboration features, since there are already good free professional-grade tools available which can work with Construct 2 projects. Save your project as a folder, and then you can use source control software to manage contributions to the project. Since project data files are XML-based, they already work with merging and diff tools. For a tutorial on setting up a source control system with a Construct 2 project on Windows with SVN, see How to collaborate on projects with SVN.