Solving Script
Hell 21

Hidden single 8 in row 6  (r6c5=8)
   r3c5<>8
   r6c5<>3
   r6c5<>5
   r6c5<>9
Hidden single 8 in row 7  (r7c3=8)
   r1c3<>8
   r2c3<>8
   r7c3<>2
   r7c3<>5
   r7c3<>6
   r7c3<>9
Hidden single 8 in row 2  (r2c2=8)
   r1c2<>8
   r2c2<>2
   r2c2<>5
   r2c2<>7
   r3c2<>8
Hidden single 8 in row 1  (r1c7=8)
   r1c7<>1
   r1c7<>2
   r1c7<>4
   r3c7<>8
Hidden single 8 in row 3  (r3c4=8)
   r3c4<>2
   r3c4<>3
Hidden single 3 in col 4  (r9c4=3)
   r9c4<>2
   r9c4<>5
   r9c5<>3
Hidden single 1 in col 5  (r9c5=1)
   r9c5<>2
   r9c5<>5
   r9c7<>1
   r9c8<>1
   r9c9<>1
Hidden single 6 in col 6  (r7c6=6)
   r7c1<>6
   r7c6<>2
   r7c6<>5
   r7c8<>6
   r7c9<>6
Hidden single 5 in box 2  (r1c6=5)
   r1c1<>5
   r1c2<>5
   r1c3<>5
   r1c6<>2
   r1c6<>3
   r4c6<>5
   r6c6<>5
Hidden single 3 in row 1  (r1c2=3)
   r1c2<>2
   r1c2<>6
   r3c2<>3
Naked double row 3 - 23
   r3c2<>2
   r3c7<>2
   r3c9<>2
Naked double row 7 - 25
   r7c1<>5
   r7c8<>2
   r7c9<>2
Locked candidate (2) in box 1
   r8c3<>2
Locked candidate (5) in box 5
   r4c1<>5
   r4c2<>5
Locked candidate (9) in col 3
   r4c1<>9
   r4c2<>9
   r5c2<>9
   r6c2<>9
Naked single 4 row 5 column 2  (r5c2=4)
   r4c1<>4
   r4c2<>4
   r5c7<>4
   r5c8<>4
   r6c2<>4
   r9c2<>4
unique 45 - 25
   r4c5<>2
   r4c5<>5
Hidden single 5 in row 4  (r4c4=5)
   r4c4<>2
   r7c4<>5
Hidden single 5 in row 7  (r7c5=5)
   r7c5<>2
Hidden single 2 in row 7  (r7c4=2)
Naked single 9 row 4 column 5  (r4c5=9)
   r4c8<>9
   r5c5<>9
XY Wing 28 - 57 num = 2
   r4c8<>2
   r5c8<>2
Locked candidate (2) in box 6
   r8c7<>2
   r9c7<>2
ER_Row1 = 1 Row2 = 8 col1 = 3 col2 = 9 digit = 6 target = 89 hinge = 19
   r8c9<>6
Locked candidate (6) in box 9
   r9c1<>6
   r9c2<>6
ER_Row1 = 3 Row2 = 4 col1 = 7 col2 = 1 digit = 7 target = 41 hinge = 31
   r4c1<>7
Naked double col 1 - 16
   r3c1<>1
   r3c1<>6
Locked candidate (1) in box 1
   r1c8<>1
   r1c9<>1
X-Loop of 1's in box 3 box 9
   r4c7<>1
   r5c7<>1
Naked single 2 row 5 column 7  (r5c7=2)
   r4c7<>2
   r5c5<>2
Hidden single 2 in row 4  (r4c6=2)
   r3c6<>2
   r4c6<>4
Hidden single 2 in row 3  (r3c5=2)
   r3c5<>3
Hidden single 3 in row 3  (r3c6=3)
   r6c6<>3
Hidden single 3 in row 6  (r6c8=3)
   r5c8<>3
   r6c8<>4
   r6c8<>7
   r6c8<>9
Hidden single 3 in row 5  (r5c5=3)
Hidden single 4 in col 6  (r6c6=4)
   r6c9<>4
Locked candidate (7) in box 4
   r3c2<>7
XY-Chain 32 11 digit = 6
   r1c3<>6
Hidden single 6 in col 3  (r8c3=6)
   r8c2<>6
   r8c3<>5
XY-Chain 42 11 digit = 6
   r3c2<>6
   r4c1<>6
Hidden single 6 in row 3  (r3c9=6)
   r1c8<>6
   r1c9<>6
   r3c9<>1
   r3c9<>7
   r9c9<>6
Hidden single 6 in row 1  (r1c1=6)
   r1c1<>1
Hidden single 1 in row 1  (r1c3=1)
   r1c3<>2
   r5c3<>1
Hidden single 1 in row 3  (r3c7=1)
   r3c7<>7
   r8c7<>1
Hidden single 7 in row 3  (r3c1=7)
   r2c1<>7
   r3c1<>9
Hidden single 7 in row 2  (r2c8=7)
   r2c8<>2
   r4c8<>7
   r7c8<>7
Hidden single 2 in row 2  (r2c3=2)
   r2c3<>5
Hidden single 5 in row 2  (r2c1=5)
   r9c1<>5
Hidden single 9 in row 3  (r3c2=9)
   r9c2<>9
Hidden single 6 in row 4  (r4c2=6)
   r4c2<>7
Hidden single 7 in row 4  (r4c7=7)
   r4c7<>4
   r6c9<>7
Hidden single 4 in row 4  (r4c8=4)
   r1c8<>4
   r4c8<>1
   r7c8<>4
   r9c8<>4
Hidden single 4 in row 1  (r1c9=4)
   r1c9<>2
   r7c9<>4
   r9c9<>4
Hidden single 2 in row 1  (r1c8=2)
   r9c8<>2
Hidden single 1 in row 4  (r4c1=1)
Hidden single 1 in row 5  (r5c8=1)
   r5c8<>9
Hidden single 9 in row 5  (r5c3=9)
   r6c3<>9
Hidden single 7 in row 6  (r6c2=7)
   r6c2<>5
Hidden single 5 in row 6  (r6c3=5)
Hidden single 9 in row 6  (r6c9=9)
   r7c9<>9
   r9c9<>9
Hidden single 4 in row 7  (r7c1=4)
   r7c1<>9
   r9c1<>4
Hidden single 7 in row 7  (r7c9=7)
Hidden single 9 in row 7  (r7c8=9)
   r9c8<>9
Hidden single 1 in row 8  (r8c9=1)
   r8c9<>2
Hidden single 2 in row 8  (r8c2=2)
   r8c2<>5
   r9c2<>2
Hidden single 5 in row 8  (r8c7=5)
   r9c7<>5
Hidden single 2 in row 9  (r9c9=2)
Hidden single 4 in row 9  (r9c7=4)
Hidden single 5 in row 9  (r9c2=5)
Hidden single 6 in row 9  (r9c8=6)
Hidden single 9 in row 9  (r9c1=9)