One of the rules for this speedrun is that no level can simulate with a score of zero for a run to count. That may seem strange, I mean how can a level simulate with a score of zero? It’s because this beautiful and amazing game has some pretty great jank built-in, free of charge!
When playing later levels in the game, there is a chance of encountering a glitch where a level simulates but no cars are driving on the road. Each level can “jam” if the traffic gets backed up without any movement, but without any cars on the road the game just scores that level as a zero. There’s no fun to the speedrun if the levels aren’t doing anything, so this must be forbidden in the rule set. There aren’t any guides or fixes on the internet that I found, and I believe that it doesn’t really happen in a casual playthrough of the game. Debugging the glitch took some time and is still ongoing, but what I do know about it is described below.
My first guess was that each level was impacted by the levels around them and by levels throughout the map screen. There is a feature unlocked when you get to the last square of levels (the full 80 levels unlocked) where you can click on a button of a helicopter in the overworld and watch a single car drive through the map as a whole, going from level to level until it gets to where it wants to go. I guessed that, if there was a blockage or slowdown in one part of the level, it may impact the number of cars going to the next level. Enough blockages or slowdowns could compound together and create traffic jams blocking vehicles. There are a few tough levels in the game that, during my first speedrun of the game, I technically completed the level right before it would have considered the level ‘jammed,” so I figured that the game glitched out enough to stop cars from going to the later levels.
I’m not 100% certain that my first thought was wrong, but testing seems to disprove that theory. I took a completed world after a speedrun and recorded each score. Then, I adjusted one level, simulated it, and then simulated each level in a row afterwards. Most levels saw no change, some levels did significantly better, and one level even ended up jamming. It wasn’t conclusive at all and felt more like random chance. However, it did spark my second theory, and it is centered around levels 4. 36. 43, and 71.
Those levels are designed to be completed without bridges, and the game should keep the player from placing bridges. However, my guess is that the code to remove the bridge feature from those levels only starts when you reopen the game after closing out of the application. If you restart the game within the application, the game doesn’t run that portion of code and you can play through the game placing bridges on those levels. On my next attempt at replicating the glitch, I restarted the game and drew a bunch of bridges on level 4, a level which I didn’t normally use bridges anyway because it was less time to keep everything at grade. Within a few more completed levels, the game encountered the glitch, and I started simulating each level with a score of zero. Before my testing, I had only encountered the glitch late in the game, around levels 57 and onward. I believe that is because I used bridges in level 43, and it eventually broke the game once I had gotten further into it.
Now, I do think that some, if not all, of the levels are interconnected somewhat. There are a few levels that do not simulate (levels 23, 41, 64, and 78 specifically) by design, they are weird levels that just bring the map together. When I first started running this game, I didn’t complete any of the levels – the levels could either be skipped entirely or just had a small piece of road draw into it to trick the game into advancing to the final level set (in the case of level 64). However, when troubleshooting the glitch some more, I noticed that I could get cars moving through the level by connecting the roadways and completing the level. Even level 23, which has no road sources or destinations in it, allowed some levels much later in the game to have better scores. I haven’t the slightest clue why this happens, but it does.
To conclude, the glitch most likely is caused by the player placing bridges into levels that they are not designed to be in, which will certainly break the game within a dozen or so levels. To avoid this, restart the game and, before drawing a single road, stop and restart the application. This will trigger the lines of code that stop the player from building roads. However, due to level interconnectivity, the performance (or lack thereof) in some levels will potentially cause the glitch. I recommend the following rule of thumb: if the level would jam if you doubled the amount of simulation time, try to get the level working a bit better. If it would hum along just fine, you’re golden. If you do encounter the glitch, try going back to earlier levels if you weren’t sure how well you did in them. If that doesn’t help much, stop, and restart the application.
