Installation
HID-Project only works with the new Arduino IDE 1.5.8 or newer. I recommend you to use the new IDE 1.6 rc1.
For Arduino Uno/Mega first install HoodLoader2 dev on your 16u2 + the needed software files. Make sure your HoodLoader2 software is up to date when you also update the HID-Project files. HoodLoader1 is only supported for legacy but will get a new use soon! For Arduino Micro/Leonardo ignore this step.
Installation has changed over the time. You don't have to modify the original core any more. Put all files into sketchbook/hardware/HID/. You have to rename the folder HID-master to HID. Do not install the files as library since it's a hardware definition, not a library.
Ensure that under 'File->Preferences' the correct sketchbook folder is selected (sketchbook, not Arduino!). Restart the IDE.
Your sketchbook folder should look like this:
If you like to, you can add the keywords.txt to your Arduino IDE so that words like 'Gamepad' are highlighted. Replace the file in arduino-1.6.0/lib/keywords.txt with the keywords.txt provided in this project.
If you want to update to a newer HID-Project version please read the documentation carefully again since the installation method might have changed (like from 2.0 to 2.1).
If you are using any dev version of the HID Project you might want to check for any updated if anything isn't working as excepted since the dev branch is frequently updated. Also make sure to download the latest HoodLoader2 board definition files if you also update the HID Project.