For decades, Nintendo fans have asked for a game that lets them create their own Super Mario levels, and so of course this has never happened. Until this week, that is; Nintendo has announced that it will bring Mario Maker to Wii U in 2015.

The demo version that Nintendo showed on the E3 floor this week is surprisingly good. You can't truly grok just how good it is until you try it on for yourself. But Nintendo's only showing a little slice of the game. And whether Mario Maker is merely good versus mind-blowing is all down to what they do with the rest of it.

Wii U's GamePad controller, with its touchscreen and stylus, is as expected a perfect control scheme for Mario Maker. You begin with an empty Mario level, and beginning to build out your platforming level is as easy as dragging items, terrain and characters down from the menu bar on the top of the screen. (You can also simply click an item, then click where you want it on the screen.)

The version shown on the E3 floor – which I believe has been stripped down significantly from the real game, so that players don't spend too much time on it – lets you place enemies from the first Super Mario Bros., although you can tweak them a little bit more than that game allowed. You can put wings on a Hammer Brother and have him pop out of a green pipe, for example, if you are a jerk.

But this is where the design process begins, because you have to playtest. And this is the genius of the Mario Maker editor. You can instantly switch between playing and editing with a single button press. So one second you're painting the screen with enemies; the next you're running and stomping on them. Doesn't feel right? One more click and you're editing again, right where you left off.

There's more than that. Every time you play, then switch into editing, you can see a translucent shadow trail of where Mario jumped and ran during your last playthrough. This makes it incredibly easy to tweak the distances and heights of your platforms, pits, and enemy placement. Let's say you want to create a platform that's just high enough for Mario to jump to. Try playing, and once you're back in the Edit mode you can see exactly where the apex of Mario's jump would be, and place a block right under it.

I used this to create some complicated designs in the span of just a few seconds. I put a series of single blocks and hovering Koopa Troopa enemies over a yawning chasm, knowing exactly where to drop everything so that Mario, running and jumping at full speed, would always land on a block.

So we know that Nintendo's gotten the actual editing portion of Mario Maker working remarkably well. The mystery is everything beyond that. First: Will there be a music editor? The Mario Paint music maker is still a beloved music tool even today. Something similar would be perfect for this, if Nintendo doesn't decide that the purity of Mario must be maintained by forcing everyone to use the familiar theme tune.

Nintendo isn't saying here at E3 how we'll be able to share and distribute our levels. If it puts too many restrictions on how Wii U users can share levels, it'll be disappointing. We should be able to freely share our creations with anyone who wants to try them.

Moreover, I think it's important that Nintendo provide tools for people to create larger, more intricate creations. I'm not as interested in playing people's Mario levels as I am interested in playing user-created Mario games. A level is not a game. A game is a carefully constructed series of levels that blend together harmoniously.

Nintendo knows this. Will it act on it? I'd love to see a game in which you choose who or what gets kidnapped by Bowser at the game's outset, or even choose a different little story to tell. I'd love to see players be able to mix and match their levels, shuffling and organizing them into a full game, and to see them be able to share that game around.

That would be the smart thing to do. It's always a crapshoot with Nintendo, though: Will we get Surprisingly Forward-Thinking Nintendo, or will we get Petrified Of The Internet Luddite Nintendo? Let's hope the latter calls in sick the day they make the decisions about where to go with Mario Maker.