A concentration puzzle, also known as a memory or matching game, is a game in which players must match pairs of cards or other objects. The two crossword solutions for the term 'concentration puzzle' are REBUS (5 letters) and RAP (3 letters). REBUS is a type of word puzzle in which words or phrases are represented by pictures, symbols, or individual letters. RAP is a musical genre characterized by rhyming lyrics spoken rhythmically over a musical background.