Sony PlayStation (PSX), part of GameDB.
PSX.data.json: All data, structured in the JSON formatPSX.data.tsv: All data, structured in the TSV formatPSX.release_dates.pdf: Histogram of release dates, stratified by regionPSX.titles.json: Mapping of serial numbers to game titles, structured in the JSON format
Most PSX games have a file in the root directory of the disc with a naming structure like SXXX_XXX.XX, where SXXX-XXXXX is the game's serial (i.e., how the game folders in games are named). This file is the game's executable, and this file's name can be trivially converted to the game's serial, which can easily uniquely identify the game. See the relevant part of the GameID PSX identification code for implementation details.
Some games have an executable that doesn't follow this naming scheme. In some of these cases, the disc's volume ID (sometimes known as the "label") contains the serial. See the relevant part of the GameID PSX identification code for implementation details.
If neither of these is the case, you might be able to use some combination of the game disc's UUID, volume ID, and file list to uniquely identify the game, but GameID doesn't currently explore those.