An interesting idea in the game is that you can exchange a track tile that's already on the board for one that you have in your hand. If there's a curve on the board, you can replace it with a Y piece (two curves superimposed) that you may have in your hand. Or, you may replace it with a switch piece (straight and curve superimposed). Seems sort of neat. But this was the trouble in our game: we didn't understand the rules of how to do this exchange. If you replace a curve with a Y, it's an obvious upgrade. Can you replace a Y with a switch? Our initial read of the rules led us to think, yes, so long as the endpoints of the tile still were connected to something. This means, though, that you it's not a simple upgrade: you could exchange a tile and disconnect another players' track (eg, perhaps the player expected to be able to take the straight track but now it's a Y). So, when do you start your inaugural run? Too soon, and another player will just break your track when you're on your last move to be done. Where's the fun in that?
Turns out that we had misunderstood the rules: upgrades can only every be that: a superset of the intratile connectivity, not just the intertile connectivity. So, a curve can become either a Y or a switch, but a Y cannot be exchanged for a switch. This single rule makes a big difference, in fact: as near as we could tell, there's no advantage to starting your inaugural run until the last tile is placed on the board, because someone else could always break your track. And at the point the last tile is played, then it's just math to see who's going to win. We'd like to try playing again with the proper rules, but it's going to be a long time before we try that.