Watch, listen, then repeat it back.
Echo lights up a sequence of coloured pads with a tone for each one, then asks the child to tap them back in the same order. Every round the sequence gets one step longer. It is a pure working-memory game, and one of the few here that a child and an adult can genuinely compete at.
The 8-10 level opens up six pads, starts at four steps, and plays back at roughly twice the toddler speed. This is the hardest setting on the site.