Setup (Qt build)

Follow these instructions to the letter and you should be able to get Python 2 games working.

Required Setup

Download the latest build or compile from source code. See: https://github.com/987123879113/pcsx2/wiki#builds
Place the SCPH-50000 BIOS in the bios folder. You must use SCPH-50000 BIOS. The exact BIOS used on real hardware can be found in MAME's ps2.zip ROMs under the filename ps2-0190j-20030822.bin (SHA-1: 0ea98a25a32145dda514de2f0d4bfbbd806bd00c). If you use any other BIOS files then you will potentially run into issues and is not a supported configuration for this fork.
Place the required MagicGate key files into the bios folder. You are responsible for acquiring these files on your own. Information about the keys can be found over at the PS2 Dev Wiki.

You must create a new .py2 file for every game you wish to add to add to the game list in PCSX2 Qt. See the PY2 Game Entry File Example page for an up-to-date example of a .py2 file.
Go to Settings > Network & HDD. Enable Ethernet and select a valid Ethernet device type and Ethernet device. Configure other settings as required here. If you are unsure what Ethernet device type to select, you can probably just select "Sockets" for device type and then "Auto" for device.
Go to Settings > Add Game Directory for each folder containing a .py2 file you wish to add to the game list. If done successfully, you should see the game entry appear on the game list.
Right click each game entry and select "Properties". Adjust the Python 2 settings as needed. Configure any other settings on a per-game basis here.
Go to Settings > Controllers. Change Global Settings as required. Go down to the Python 2 tab and configure inputs for the Native input method here.
Once you've configured your network settings, imported the .py2 game entry to the game list, and configured your controls, you should be able to launch the game by double clicking the game entry on the game list.