Have the computer score every move to a depth of 16 ply(moves) then look for radical shifts in the scoring. A sudden swing from +1.4 to -4 means there was a bl

Have the computer score every move to a depth of 16 ply(moves) then look for radical shifts in the scoring. A sudden swing from +1.4 to -4 means there was a blunder. You set the ply shallow because no beginner is seeing more than 8 moves ahead, most masters can’t in most positions. Fritz and scid etc also have mark tactical exercises modes that so the above automatically.