I think there is currently no way to easily indicate suggested minimum age for players.

And it is not about some adult\violance content as some games themes requires some general knowledge from the player or topics are more complex than let say for 10 old years players.

It would be nice to have some icon (like rating icon) with suggested minimum age where developer may indicate to whom game is targeted.

Like 0+, 3+, 7+, 13+, 15+, 18+ etc.