How to boot games off USB on a ps2? (OPL Method)
You will be needing some additions rather than your ps2. Firstly the most important, you will have to get your ps2 mod chipped or you must have a swap magic disc or an exploited memory card and a USB hard drive (Which has an external power source). You can use pen drives but the performance will be horrible and most of the games will not run. Now you need the apps, they are uLaunchelf cd/dvd or on your exploited mmc, download from here. This will help you to execute the app. Now download the this software from here. The software is called OPL or open ps2 loader. This will help you to execute the games from your external hard drive.
Now comes the slow part, ripping games to the hard drive. There are two ways to do this. Either rip them into the USB extreme format or simply make the iso files of the game as the new version of the opl has features to execute the iso file. Download this software from here. Now you will get a zip file, open with any compatible software and extract the file.
When you will open this file, you will get a program like above. Now format your external hard drive with this software in the disk format section. To install the game on your hard drive, insert your ps2 cd/dvd select cd or dvd in the program, type the name and select start install.And also copy your opl file into the hard drive. After installation disconnect your hd and lets come to the ps2.
Boot with your desired method and open the ulaunchelf.
You will get a screen like this, select file browser, select mass, select the opl.elf from there.After that u should see your OPL(Open PS2 Loder)screen just press X on USB games,if u have done all things correctly u will see your games just press X and enjoy.