What qualifies as a clone?

There's a lot of subjectivity in deciding whether a title is a clone of another. Retool follows these guidelines to identify clones when looking at a set of titles:

• Revisions, rereleases, and preproduction variations of the same title.
• Titles that are identical aside from their title screen or the languages available.
• Titles with only cosmetic differences, such as reskins or sprite swaps.

The decision isn't always clear-cut. A game might not qualify as a clone, for example, if it has unique levels or gameplay attributes that aren't a superset of another title. Every situation is approached on a case-by-case basis.

Demos are not considered clones of their complete variants. This is because some demos provide a unique experience not replicated in the full version of a game.

BIOSes are never considered clones of other titles, even if they contain games, come from different regions, or are different revisions. This is because some emulators can be sensitive to the BIOS being run in combination with a particular game.

Remasters and remakes are usually considered their own games.