[vintermann]

Yes, 5x5 is small enough that all backtracking can be codified into easily human-accessible rules.

* 5, 0, 1 1 1, 2 2, 3 1 and 3 1 are immediately solved

* 4 lets you set 3 squares immediately

* 3, 2 1 and 1 2 let you set 1 square immediately

[jobigoud]

In summary the only ones that don't let you put a square immediately are "0", "1", "2" and "1, 1". And as soon as you put a square you can put some crosses (right click). In the end it becomes fairly mechanic.

[Ancapistani]

100 puzzles in, and I've not had the need for a manually-placed cross, either.