What it teaches
The English words for the colours, tied straight to the colours themselves. There is no Polish anywhere in the game, and that is deliberate: a child who learns red as "a word that means czerwony" has to make two steps every time, and the second step never goes away on its own.
How it works
Words sit at the bottom of the screen and coloured cups sit above them. The child drags a word onto its cup. The word is also read aloud, in English, when it is picked up.
A wrong cup does not accept the word: it shakes and the word goes back. The drop target is outlined in ink rather than green, because green means correct everywhere else and a child dragging the wrong word over a cup should not be told they are right.
What to look for
Drag works with a finger, a mouse or a trackpad, and a tap on the word followed by a tap on the cup works too — some children tap rather than drag, and both have to work.
This is the easiest game in the subject and a good first one for a child who has met no English at all.