When Sony initially announced the final list of 20 games that would be available on the PlayStation Classic, we warned that the selection was full of “glaring omissions” that “might annoy you.” A quick analysis of the source files for the system’s open source emulator, though, suggests that many other well-remembered PlayStation games were at least considered at some point in the hardware’s development.
Sony has published the source code for the many open source components of the PlayStation Classic to comply with the requirements of the GNU General Public License. That includes source files for a modified version of PCSX ReARMed, an open source PlayStation emulator with a long history. You can also see how the PlayStation Classic files differ from a “clean” install of the emulator at a glance using this Github page.
Buried in the system’s “title.h” file is a list of enumerated variable names and associated PlayStation serial numbers referencing various games. That list includes all the games packaged with the PlayStation Classic (in both Western and Japanese markets), as well as dozens more that are not included in the box. Elsewhere in the source code, many of those variables (including ones for unplayable games) are used to modify certain emulator settings when that game is selected.