There is an easy kind of brilliance to Nintendo at its best - although I'm sure there is nothing easy at all about creating this sort of impression in the first place. Anyway, it's down to a sort of pulling together of all parts of a game's design, reeling things in until what you have in your hands in rich and coherent and easy to understand. Last week Nintendo was showing off its forthcoming single-player stuff for Splatoon 2, and the sense throughout was of that richness, that coherence, and weirdly enough, the welcome surprises it can allow for.

Coherence! You already see this sort of thing in Splatoon in the way that ink becomes territory and territory becomes safety, a speed boost, and the ability to refill ammo. Splatoon's latest offering is a suite of single-player levels called the Octo Expansion. It's based around the conceit of a trip on the underground, as far as I can tell, each new mission starting with you standing before turnstile gates and paying to pass through into...what next?

Oh man, great stuff awaits, all of it familiar, all of it surprising. Take the Baller, a stand-out power-up from the multiplayer, in which you get to spend a few glorious seconds rolling around inside a massive hamster ball before triggering it to explode in a shower of ink. The genius of the Baller in the middle of a match is not just that it's handy but it's so desirable: you want it so much, and when you get it, it's yours for a matter of seconds and then it's gone.

Complex levels, each built around a single neat idea: cor!

So what would happen if you had an entire level of the Baller? What would happen if every time you triggered the explosion you were back in another Baller again? Well I guess the level would have to be a sort of assault course, right? With ramps and jumps and slow-moving missiles? And I guess as well as enemies it would have to have a fearsome time-limit to stop you from just exploding your way across the landscape, in order to make each explosion a risk as well as a reward?

It works beautifully, and then it's gone and the Octo Expansion takes you somewhere else: to a pinball machine where you have to spray paint to keep a giant 8-Ball moving through the metal loops and chicanes, to a sniper's paradise where you sit on a moving platform that rotates when you snipe certain parts of the landscape, and which is surrounded on all sides by enemies sniping back at you. To a jetpack section where you can only stay afloat when your ink-jets are boosting off solid ground, and to a sort of horde mode in a confined space where you must see off waves of baddies using only a bucket of ink - but wait? Too easy? How about chucking in the fact that the surface beneath you is made of crates, and each miss with the bucket of ink will leave gaps that you then have to navigate?

Expect plenty of this in the final expansion, a suite of variations that are wildly inventive, that challenge the notion of what Splatoon is at heart, and which all, somehow, make total sense, because they build cleverly on bits and pieces that are well understood. The Splatoon Variations! Yes please, Nintendo. That sounds lovely.