Press Win+R to open the Run dialog Run %LocalAppData% Create a directory SEGA if it doesn't exist yet. Open it. Create a directory PHANTASYSTARONLINE2_NA_STEAM if it doesn't exist yet. Open it. Create a file name steamupdate.txt by right clicking > New > Text Document (IF FILE EXTENSIONS ARE HIDDEN IN YOUR EXPLORER, JUST NAME IT steamupdate) Open it in Notepad Put the text v70000_rc_135
Voila. Your launcher will work again. Repeat these steps if it breaks.
It works, nice dude.