For anyone who just wants a sense of what the game is like without the fuss of playing it, here is the launch trailer: https://www.youtube.com/watch?v=35nDYoIwiA8
They should, in my view, have had y as a function of t, and dropped x. Or another solution that doesn't create confusion.
I also think it's weird that changing the equation changes the shape of the mountain, but the text is about changing the path of the sled.
Then you could have only had a flat floor that moved up and down. If you need shape that changes, you need it to be a function of both x and t.
So e.g. (x-t)^2 / 5 is a parabola shaped "bowl" that moves right at 1 unit per second.
In later levels, you use t to make a floor that actually moves.
The relationship between y and x is the coordinate plane behind the level (you can hold down right click to see it, IIRC).
Instead they say the task is to set path of skier - i.e. how the skier goes down the mountain. But that's not correct - the skier obviously doesn't need to just follow the mountain top. Common sense/reality is the opposite - you rarely just follow a mountain top.
If they'd just said the above, and I think not shown the value of t, it would have been a lot clearer, at least to me.
If in later levels they show formula(s) using gravity, and perhaps show the skier on different planets, with different values of G, then I can see the value in showing the value of t. But as it is, I think it's confusing.
But even ignoring that, nowhere does it define the relationship between t and x. What I assume they mean but don't say is that x=t. That's arbitrary.
Also I assume you mean the path of the sled is (t, f(t)) where f is the function defining the slope. If the path of the sled had a value of (x,y) it would be stationary :)
Perhaps "the shape of a path down a mountain" would make everyone happy.
If they'd just said the above, and I think not shown the value of t, it would have been a lot clearer, at least to me.
If in later levels they show formula(s) using gravity, and perhaps show the skier on different planets, with different values of G, then I can see the value in showing the value of t. But as it is, I think it's confusing.
It definitely has a few rough edges, though. The equation in the first screen has the right behavior but is complex enough to probably be concerning for the target audience, and I'm not sure it clearly spells out what the player is going to be doing in the greater game. `y = x` is a great actual starting point and it clicked for me then. I'm not sure how to thread that first-level needle from a design perspective, to be honest.
Again, though, I do really like it. There's some trial-and-error on each level (at least for me) but I think that's part of what could make it an effective learning tool.
Clicking on the button that says "click here!" has no effect.
Clicking on the equation allows me to change it; this changes the slope of the ski slope. I think what's supposed to happen here is that when you change the slope under the sled to be non-horizontal, the sled should start moving — sliding down the slope you just created, toward the second snowman. But that doesn't happen in Chrome.
Clicking on the mountain leads to what I assume is a level-selection screen; I didn't investigate further.
Clicking on the gear leads to a settings screen; I didn't investigate further.
There's no obvious tutorial or "help text" button.
Also, the site doesn't really deal with the browser's back button correctly. I'm not sure what it's doing, but it seems to fill up the history with instances of itself, maybe on every click, which made it... more difficult than necessary... to get back to HN afterward.
The map should zoom with scroll, is that not working?