Continuing game progress works via a password system. Often used in systems with no permanent data storage available & carried over to other platforms via crude ports
Alternate name: Level codes
The first video game about Save Passwords was released in 1975.
If data needs to be stored in a password, this requires that it be generated from said data. This is generally known as a way to "save" a game including all important conditions of the characters and the game world; data usually lost with "level codes". Thus they are called "save passwords" or "password saves" or even "recorded progress". Most of these type of passwords encode the data, not just to obfuscate it and keep players from creating or modifying a password (to change their character inventory or stats for examples), but also to shorten the length of the password which is generally much large than 9 alphanumeric and probably also symbolic characters. With these types of passwords, the same conditions (from the players perspective at least) might actually be recalled from many different passwords. Such password encoding systems sometimes have checksum values included in them. Again, this discourages players from hacking passwords, but as a practical matter, it ensures that invalid data is not recalled as this could have adverse effects like crashing the game. Time data and/or random data might be encoded into these passwords even if such time data does not effect the game. This has the effect of generating a practically unique password for every save every time and can further obfuscate the password system to discourage hacking.
Passwords (with extremely unbelievingly rare exceptions) have the advantage of being easily transferable between different copies of the game. As in, one can share a password for a given title and all owners of the that title can use that password on their copy to recall the same conditions as when the password is used on the copy that reported it. This is the case even with generated passwords that store data. Both "level codes" and "save passworda" can be used cross-platform should the developers choose to use the same list of "level codes" or ensure that the password system generates and accepts the same data in the same way. While this is uncommon, it happens a lot more often transferring other save types between platforms, such as save RAM data or even save files on magnetic disk.