What it teaches
The order of the alphabet, which a child needs long before they need it for a dictionary — it is the backbone every other letter task hangs on.
The letters are spoken by name: ay, bee, see. Some browser voices say "capital C" when handed a bare letter, which tells a child about a distinction the game does not offer, so the names are spelled out instead.
What to look for
This is the first game to try with a child who is five. It asks nothing about reading and nothing about meaning — only about order.