How to play

The grid uses three symbols: ▲, ■, and ●.

Every row, read left to right, must combine to the target symbol shown at its right edge.

Every column, read top to bottom, must combine to the target shown at its bottom.

How symbols combine

Use the small table next to the grid. The key things to remember:

■ + anything = anything (■ does nothing)

▲ + ▲ = ●

● + ● = ▲

Combining a whole row

Take the row's symbols one at a time, left to right. For example:

▲ ● ■ ▲ ▲ = ?

First combine ▲ + ● = ■.
Then ■ + ■ = ■.
Then ■ + ▲ = ▲.
Then ▲ + ▲ = ●.

So this row resolves to ●.

Solving a blank cell

Blank cells are shown in a darker shade. Suppose this row needs to resolve to ●:

▲ ■ ? ● ▲ = ●

Combine the symbols you know, working around the blank:
▲ + ■ = ▲
● + ▲ = ■ (combining the two known symbols on the right)

So the row reduces to ▲ + ? + ■ = ●.
That means ? must be ▲, because ▲ + ▲ + ■ = ●.

Every blank sits in both a row and a column, so check both as you go.

Playing

Tap a blank cell to cycle through symbols. Tap the small corner of any cell to leave yourself a private note. Press Check when you're ready. Correct rows and columns will turn green. You have three attempts.