| ... | ... | |
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| 18 | 18 | Set 2 includes Worlds 7–12, for a total of 6 worlds. The levels of Set 2 are harder than those of Set 1, but are easy enough with sufficient pratice. |
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| 19 | 19 | == Xtra Levels == |
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| 20 | 20 | Xtra levels do not have unique titles, and follow the naming format of \''''World X_'''\'.[* Collaboration levels are an exception to this.] |
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| 21 | | The blank is filled with a single letter, which is usually taken from the song title of the boss level. Normally, the first level is used[* e.g. [[World XO]] - '''O'''ne Forgotten Night], but certain titles have overlapping first letters, causing subsequent letters to be used instead[* e.g. [[World XT]] - Op'''t'''ions]. |
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| 21 | The blank is filled with a single letter, which is usually taken from the song title of the boss level. Normally, the first letter is used[* e.g. [[World XO]] - '''O'''ne Forgotten Night], but certain titles have overlapping first letters, causing subsequent letters to be used instead[* e.g. [[World XT]] - Op'''t'''ions]. |
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| 22 | 22 | |
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| 23 | 23 | === [[/Xtra Island|Xtra Island : Xtra!]] === |
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| 24 | 24 | [include(틀:자세한 내용,문서=World/Xtra Island)] |
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| ... | ... | |
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