SCUMM/HE: Blue's Birthday - Carrying over Red/Yellow CD savegames (fix included)

[fusefib]

Blue's Clues: Blue's Birthday Adventure is a two-CD game with four pathways, two on each disc. The original behavior is that savefiles are partially common for both CDs. In the original game, the following savefiles are generated:

(for Yellow CD)
Blues1.nam
[PlayerName1].bca
[PlayerName1].sga
[PlayerName1].sgb
...
(for Red CD)
Blues1.nam
[PlayerName1].bca
[PlayerName1].sgc
[PlayerName1].sgd
...

Blues1.nam and [PlayerName1].bca are shared between the CDs and contain the game profile, i.e. sign-in information and overall game progress across e.g. minigames from all four pathways. The .sga to .sgd files are pathway-specific savefiles that get generated once you enter a pathway and the game saves progress. [PlayerName1] is whatever gets chosen.

ScummVM generates the same type of savefiles, but its behavior is to add "[gameID]-" as a prefix to these savefiles, and to increment gameIDs (or targets) when adding what is considered ID-wise the same game. With the Yellow CD and Red CD being considered separate games with one default gameID, we get "BluesBirthday-" and "BluesBirthday-1-" as default savegame prefixes, thus:

BluesBirthday-Blues1.nam
BluesBirthday-[PlayerName1].bca
BluesBirthday-1-Blues1.nam
BluesBirthday-1-[PlayerName1].bca

The result is needlessly getting separately loaded game profiles and progress by dint of not loading the same files, when ScummVM would otherwise manage common savefiles for both game entries just fine.

Here is a proposed fix to easily restore original functionality:

​/engines/scumm/he/script_v60he.cpp#L155

    // Prepend the target name
    filePath = _targetName + '-' + filePath;

->

    if (_game.id == GID_BIRTHDAYYELLOW || _game.id == GID_BIRTHDAYRED) {
        // Prepend generic name for shared game profile between targets
        // for Yellow CD and Red CD of Blue's Birthday Adventure
        filePath = "BluesBirthday-" + filePath;
    } else {
        // Prepend the target name
        filePath = _targetName + '-' + filePath;
    }

Per MD5s and detection entries, there is only one known Red version and Yellow version of the full game and demos don't create these files, so probably zero compatibility issues on that account.

The prefix remains useful so users can distinguish these savegames among other ScummVM saves as well as partial overlap with the existing default naming.

A minor drawback is the "BluesBirthday-1-" progress gets reset to zero, unless the user manually swaps the savesets which would still exist. I would say the drawback is minimal and the possibility of restoring game profiles by renaming can simply be documented in the game's Wiki entry.

A seamless user experience fix might be to newly add a game configuration key by default (e.g. boolean "sharedsaves") when adding these games going forward, and to add a check for that configuration key in the code above. This way, (the other half of the) existing entries will continue to work with the current savegame naming convention and newer entries will have shared game sign-in and progress by default. However, this needlessly clutters the code.