Under the orders of the evil swamp witch Metallia, in The Witch and the Hundred Kniight, you play as the titular, yet grammatically awkward "Hundred Knight" (a single person), who's on a mission to help Metallia spread her evil swamp as far as possible throughout the land. Confined to the swamp, Metallia wants to seek revenge on the people who trapped her there, and see the world in process - so it's up to you to march across the land, on a quest to find and activate as many of the plant-like 'pillars' as you can - with each one helping to spread her beloved swamp mud further and further afield.
Much like other button mashing role playing games like Diablo, most of your time with the The Witch and the Hundred Knight will be spent spent exploring the twisting and turning forest paths, beating up bad guys and loading up on the increasingly powerful and rare equipment they drop - with each level culminating in a boss fight against a more powerful foe. Beat up the baddies, activate the pillar, and defeat the boss, and you'll help your evil mistress spread her swamp further into the world, in an interesting twist on the standard anime style story.
While much of the game is simple enough for younger children to understand, the concept of the Gigacals - a unit of energy which constantly depletes during in each level, effectively working as a timer - may pose a bit of a problem for some younger children, as it effectively works as a time limit for each mission, which can hamper the amount of exploring you can do. While you can't switch it off, there are a number of things you can do to restore your lost calories and gain extra time, whether you're exchanging points you've earnt for extra Gigacals when you come across a pillar, using items, or consuming regular enemies - although you'll always have to keep an eye on the timer, to check it isn't getting too low.
Other aspects of the game may also sound overly complex at first, especially to younger players. With a fair amount of reading to be done, and only partial voice acting, the fact the game throws so many systems and sub-systems at you may be a bit intimidating for some younger players - even if you can safely ignore the vast majority, and concentrate on beating up the bad guys. With a million and one different forms of points you collect, two separate inventories and a choice of title and sub titles that can help you tweak Hundred Knights stats, most of it is pretty superfluous. So long as your child understands how to switch their old equipment out for the shiny, new, and more powerful swords, spears and such, they'll be fine.
A combination of Metallia's foul mouth and publisher NIS's staple boob jokes and crude humour, The Witch And The Hundred Knight isn't exactly the cleanest of games. Pretty much every swear word imaginable crops up at various points in the dialogue, only occasionally being censored out with symbols and beeps for comedic effect - "It's Metallia, you stupid $%&#? bitch" etc. There's also a fair helping of innuendos strewn through the cutscenes, as well as a rather dodgy section in which a buxom female is bound naked, partially covered by a swampy mist whilst Metallia declares that "your stupid tits are each the size of a whole cooked turkey" before ordering Hundred Knight to "shove this right up that dog's swampy ass" (followed by a black screen and the odd yelp of pain from the poor princess).