Once you have created a game for the Windows 8 platform and tested it on your development x86 machine, you'll probably want to test it on a Windows RT device too, to ensure that the touch controls etc... are all working as designed. However, to do this can be a bit of a complex process, so this article will take you through the steps required to get your games up and running.
Before You Begin
Before starting on the process, you will need to download the attached AppXInstallScripts.rar file. This rar file contains some scripts which GameMaker:Studio will need to run as part of a build to install the package. You will need this file downloaded to your PC and extracted to safe location for future use.
Once you have downloaded that, you should then ensure that your Surface is able to "talk" to your development PC over the local network before you can proceed.
Building Your Game
Assuming that you have your game already working on the Windows 8 target platform, then to build your game you will first need to change the setting for the "Native CPU Target" in the Global Game Settings Windows 8 tab (as shown below). This determines the type of package you would like GM to export, and should be set to the ARM package.
Once you have made this change, simply build your game using the Create Executable button. Note that at the end of this process you will get shown an error that the final game file could not be installed on the computer - this is quite correct, as your PC won't be able to install the RT package to itself, since you have built for ARM processors.
You should now browse to the location where you saved the game output file/folder and move it across your network to a convenient location on your Surface device.
Scripts and Certificates
Since you are developing for Windows 8 you will have generated a certificate which your game is being signed with as part of the build process. this certificate also needs to be bundled with your game, otherwise if you don't move this certificate over also you can't install developer versions it on your Surface. So we now need to export your details as a certificate file.
To get this you must first open up Internet Explorer (not your favourite other browser!) and go to its Internet Options from the settings drop-down menu. From here, go to Content, then click the Certificates button.
From the new window that has opened, you will need to switch to the Trusted Root Certification Authorities tab and find your certificate in the list - it'll usually be called the same as your PC's name, but may be the same as your MS Account. Select it and then choose to Export it.
When you hit the Export button, it will start an export wizard which will guide you through the rest of the process. Note that in the wizard you need to select the default export file format and you can name the file whatever you wish. When finished, you must browse to the new file certificates file then cut and paste or copy the *.cert file into the folder of scripts that you unpacked earlier (see Before You Begin, above).
This folder of scripts must now be moved over the network to the Surface device also. With that done, you must then put the game's output file/folder 8that you copied over in the previous step, Building Your Game) inside the same scripts folder so it sits next to your certificate and scripts files.
Can't find the certificate? Then Instead of looking in IE hit Windows + R and run "certmgr.msc". All of your certificates should be available here, with the signing certificate being found in the folder labelled "Trusted people", but yours may be elsewhere.
Installing Your Game
To actually install your game on the Surface, you must open the folder of scripts and double-click the file Add-AppDevPackage.ps1. This will spawn a command window and run through some automated tests on the package (which it should all pass). It will also check your certificate file, which may mean that you will be required to confirm the certificate details, etc.... before continuing. Finally, press return when it asks you to and after a short wait your package will have been installed, with a shortcut to your game on your Start Menu.
After this you won't need to re-make your certificate again, and you can just move versions of your game over and install any updates as necessary - be advised, however, that you may well need to remove any existing copy of your game before the new one will install.