This "engine only" package is a 120 MB download, rather than 1000 MB for the advanced installer. It does not include "Advanced Services (Full Text Search and Reporting Services), nor the Tools.
This package depends on the dotnet 3.5 package because the SQL Express installer seems to have difficulty resolving this dependency consistently on its own.
This package includes the SQL installer switches to do a default install with no instances as such:
/Action=Install /Role=AllFeatures_WithDefaults /IACCEPTSQLSERVERLICENSETERMS /Hideconsole /INDICATEPROGRESS /Q /UPDATEENABLED=FALSE
The use of the "/Role" switch allows you to use additional switches to configure an instance while installing this package. A typical example is as follows (all one line - notice chocolatey style escaping that uses two single quotes for double quotes in sql setup switches.):
choco install sqlserver2008r2express -installargs ' /INSTANCENAME=YOUR_INSTANCE_NAME_HERE /SECURITYMODE=SQL /SAPWD=''SomePassword'' /BROWSERSVCSTARTUPTYPE=Automatic /SQLSVCSTARTUPTYPE=Automatic /SQLSVCACCOUNT=''NT AUTHORITY\Network Service'' /SQLSYSADMINACCOUNTS=''BUILTIN\ADMINISTRATORS'' /AGTSVCACCOUNT=''NT AUTHORITY\Network Service'''
If you want to see progress add -InstallArgs '/INDICATEPROGRESS' when calling this package.
There is much more information about the many switches that can be used at installation time here: http://technet.microsoft.com/en-us/library/dd981032(v=sql.100).aspx
Tested on: Server 2012 R2