But, being a 1D game with jumping over entities wouldn't really be breaking the 1D aspect, just like giving Dwarf Fortress a z-axis doesn't make it a 3d game. It's representative. The entity isn't actually jumping over the object in a new dimension, it's just a cheap explanation for being able to pass through it. Like in those games when you press up to enter a door or something, you're not actually going along a z axis into another room, it's just a convenient explanation for teleporting to another place.
Though, since the z-axis of DF DOES affect gameplay in a 3D manner (dwarfs can go up and down levels of the fortress, for example) DF can now be considered a 3D game with 2D representation. And so a game with instances on a line that can move over eachother would be a crude 2D game with 1D representation, just with very limited movement on the second axis, but it's still there.
As for teleportation, I like to imagine that instantly teleporting from one point to another without having moved in a line through the space would imply an extra dimension the object is moving in. Picture, for example, the line world of the 1D game. Say an entity teleports instantly from one point to another. One could say that the entity first leaves the line, then moves in another dimension, then returns to the line in another spot. For the other entities of the line the instance teleported instantly since there was no movement through their limited space and they can't be aware of this other dimension.
In this case I must correct my previous statement by removing the teleportation bit.
Of course, I'm taking about a very strict way of seeing this.
You guys feel free to ignore me.