The shopper describes what they want by colour and size in the new language, figure out which item they mean.
At a market stall, a shopper describes an item by its attributes, colour, size and category, in the foreign language. Read the clues, work out which single item on the stall satisfies all of them, and pick it. The clue set always points to exactly one answer, so it is pure deduction once you parse the words.
Market Haggle blends descriptive vocabulary with logical elimination, so words are learned through reasoning.
Working out which item a shopper means from attributes given in the target language is communicative language teaching: using the language to accomplish something rather than to display it.
Making comprehension the puzzle is the original design.
You cannot answer by recognising one word, because several items share each attribute and only the combination identifies one. That forces real parsing of a sentence, which is what communicative approaches are trying to provoke.
Market Haggle is an original, free browser game that blends descriptive vocabulary with logical elimination. It is built in-house and runs instantly in your browser.