Choose the TYPE of problem

Level 0 - Mainly kids stuff

Smaller and simpler than standard 9X9 sudokus

Level 1 - Standard 9X9 or equivalent

These are the regular types that are normally solved

Level 2 - More complex geometry

Some odd shapes and may wrap side to side and top to bottom but not both

Level 3 - More complex still

Geometry can wrap side to side and top to bottom