Jeremy Rand has updated his 2015 Hackfest winning entry A2Sudoku to version 1.2 — you can get a .DSK image directly from here:

The main change is that when you enter a value, any scratch values in cells in the same column, row or sub-square are automatically updated. So, if you enter a “5” into a cell, 5 will be removed as a possible scratch value automatically from all cells in the same column, row and sub-square. Makes it a bit easier to keep your scratch values up to date when the program does a bit of it for you.