BUG+n
At least one extra candidate is true, so candidates incompatible with every extra are removed.
How it works on this board
A pure BUG has two solutions, so at least one highlighted extra candidate is true
5
1
4
3
6
2
1
6
8
7
5
4
6
9
5
1
2
6
4
1
7
1
2
7
4
6
7
4
6
3
1
9
5
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2
8
3
1
6
2
6
1
3
2
9
2
5
9
6
3
1
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