Easy as ABC
Also called Letterraam, End View
Put each letter once in every row and column; letters outside are the first one seen.
Rules
Every row and column has A, B and C exactly once; the other cells stay empty.
✓ One of each ✗ B twice A letter outside is the first one you meet looking in from that side.
✓ B comes first ✗ A isn't first
Example: First Letters
Playing here: Tap a cell, then a letter (or type it). Erase leaves a cell empty.