Mahjong Mysteries is a simple collection of mahjong solitaire puzzles, themed around Ancient Greece. Easy to pick up and play, with over 400 puzzles on offer, and a variety of different game modes, each of which offers its own twist on the standard mahjong experience, there's plenty to keep you busy here.
As far as how easy it is for children to pick up and play - the game does explain how you're meant to play mahjong, but it's a written explanation, rather than an interactive tutorial. If your child isn't that great at reading, but understand the rules of mahjong solitaire, they'll likely pick it up pretty quickly here - but if not, reading skills are required. Other than that, it can be a little bit fiddly to select the right tile at times, which younger players may find frustrating - although it is a lot easier on a DSi XL. The only other initial problem younger players may have is that for some tiles, you have to match them by theme rather than being identical - for example, you can only match a tile with seven pillars on with another tile with seven pillars on, but you can match and orange torch with a blue torch, which initially seems a bit odd.
Completely devoid of blood, gore, swearing, or any sexual content, there's nothing for parents to worry about in Mahjong Mysteries: Ancient Athena.