Normal 4x4 Sudoku rules apply and all variants are standard.
4x4 Sudoku: Place the digits 1-4 once each in every row, column and box.
Prime Neighbours: Every pair of orthogonally connected cells sum to a prime number.
Arrows: Digits along an arrow sum to the number in the connected circle. Digits may repeat along a line if allowed by other rules.
Solution code: Column 3, top to bottom
on 23. June 2026, 21:32 by Onkel_Dagobert
26 sec.
on 23. June 2026, 20:26 by SanFranSam
Not by me. 2:47
on 23. June 2026, 00:16 by Myfyr MJ
Very nice and very easy - 39 seconds but I guess that time could easily be beaten.