The available options do the following.
Launches the Sandbox Editor associated with the project. You can then open a level from your project by going to File -> Open
Launches game mode for this project.
|Launch dedicated server|
Launches the dedicated server associated with this project.
Packages the project to a standalone build. All files that are required for the GameLauncher are moved into the build folder, together with the assets which are filtered and packaged into .pak files.
Generates the metadata (.cryasset files) for the assets of the project.
Generates your code solution for C++ and C#. The solution will need to be regenerated if the project is moved to a new hard drive location.
|Open CMake GUI|
Opens the CMake GUI at the location of the project. This requires a CMakelist.txt file to be in the code folder of the project. This can be used to adjust the CMake settings when generating the solution.
|Switch engine version|
Lets you change the Engine version you use for the project.
The Engine versions that appear in the drop-down menu are the versions that you have installed.
If you have downloaded an Engine version from GitHub, you can select it here by choosing Switch engine version and then clicking the Browse button in the menu that appears:
You can then browse to the location where you've saved that Engine version. This simply needs to point to the root folder of that CRYENGINE version.
Adding Console Variables and Console Commands