Logic Masters Deutschland e.V.

I - Okay, there's the tonic.

V - That makes sense. Wait, this isn't a...

vi - Oh, no...

IV - *sigh* Of course, another four chord song.

Fillomino: Divide the grid into regions such that each given digit specifies the number of cells in its region. No two regions of the same size may share an edge.

Four Chord Loop: There is a loop in the grid that passes at least once through every region of size 1, 4, 5, or 6 and never passes through any region of any other size. The loop never enters the same cell twice and must always pass through regions in the order 1 5 6 4.

Penpa+: https://tinyurl.com/25hw8dsv