A Xmas tree with 81 candles to light.
The symmetric tree consists of 17 Sudoku's of which 3 Asterisk, 1 Girandola and 7 SudokuX grids.
The 17th grid is an "Explosion" or Center-Dot vanilla/normal Sudoku, colored yellow, symbolizing the 81 candles.
The yellow cells however are not in the middle of other Sudoku boxes, because it would overlap too much with Asterisk of Girandola.
Overlapping areas are colored darker green
Best is to download the image and print it. The actual size of the image is 2021 x 1902 pixels
https://www.dropbox.com/s/4lx3fmpztw9eyrx/Xmas2018.png?dl=0There is also the same Xmas tree with Pencil Marks to be viewed and downloaded
from
https://www.dropbox.com/s/o05ge6fvogdpbun/Xmas2018_pm.png?dl=0.
The puzzle should be EASY, because no additional methods are needed, except hidden or naked singles, but it appears not so easy. During the process and using no additional methods you end up in a situation where only 1 or 2 cells can be solved among more than 700 other empty cells. But which cells ? And that happens several times.
Then additional methods like naked/hidden subsets or Pointing Pairs etc come in handy.
Pretty moderate for such a large puzzle with 879 empty cells to solve. That's the challenge.
Happy solving. Have a nice Xmas and a prosperous and healthy 2019.
In code:
#17//U6,A/O18/AA18/L30,X/AD30,X/U42,GX/I42,A/AG42,A/F54,x/O54/AA54/AJ54,x/U66,x/C66/AM66/U78,X/M28,N-2
500000004900374005003000900600205009400000001000000000000000000000000000000000000
070000000009308000008050000000000050000093200000501608300200040000030100000000000
000000060000108500000050900070000000006740000504309000020003005008060000000000000
007300200006000030000000000040000050000800000000003000000000010000000000000000000
003005100060000800000000000020000060000002000000400000040000000000000000000000000
010000080000000000000000000000000000000000000800000009400523006000010000000000000
015000000000000000080000000000000800000640000000005003000000000000400010000000000
000000170000000000000000050007000000000037000100600000000000000070005000000000000
000000000000000400000000000000800009000000080060000000000000708000000000000400300
000006400010000000000000000009000002208000600000000000020007000500000000000300000
006500000000000070000000000400000500009000108000000000000100080000000006000004000
000000000005000000000000000300001000090000000000000010509000000000000000004002000
000000000000000000000000000000000000000867000000000000000000000000000000004000800
017000000420000000000000400000000006003920000041060300304000000070005009060017520
000000910000000087002000000200000000000092600006010890000000509900500070035820040
000000000000000000004000800008502600000000000040000090000108000000000000000000000
000000000000000000000000000000000000000000000000000000000000000000000000000000000
Warning: Grids 6 and 7 are switched in the code. Same with Grids 13 and 14
Edit: url's and images redirected to dropbox
