As of 01/JULY/2022, out of all official 2,435 software titles PSIO is so far 99.5% compatible.
For more detailed information, please see our ‘Compatibility‘ database on JIRA (NOTE: “Wipeout XL/2097” and “Crash Team Racing” are perfectly playable, but have minor issues).
If you’d like to know how we got this 99.5% compatible calculation, take the games listed in JIRA that do not work at all, and minus it by the total amount of PSX games (IE: 2,435). Then, divide those two numbers and get the percentage (example).
There are some games which may also have problems that have been reported on our Forums, and you may see the list and follow the reports here.
Please note that as we tweak and work to improve the code accuracy of PSIO, some firmware updates may break games that were previously working. Do not worry however, we always manage to fix them in a later update. It is critical that you use the latest firmwares and report any problems to us so we know about them.