OpenLoco v24.02.1 is out! In 24.02, there was an issue with newly placed train stations, where it would set the height clearance of the station and the track to 0. This would even happen when hovering a station ghost over the track. With zero clearance on the station and track, buildings could accidentally be built over the top of the track, or other unexpected results.
To understand how this mistake slipped in, you need to understand how our semi-automated replay verification works. Whenever we add a new bit of code, one of the ways we verify we haven’t broken anything, is we run the game with a known save. After a known number of simulation iterations, we then verify that we can produce a save file identical to a reference save. We rely on the AI in the simulation to exercise the code paths of the new code. This isn’t foolproof, as the AI does not always perform every action, but it happens that the station clearance issue should have been detected by this method.
Unfortunately, though, in 24.02 we added the train station placement game command, and this command had a number of original AI related bugs that were fixed. So we were expecting non-identical saves, and didn’t investigate fully why it diverged from the reference.
Fortunately, @memellis has been working on a save game comparison tool, which should hopefully be ready for the release after this. If we had used such a tool, it is likely this issue would have been noticed.
Anyway, the issue has now been found and fixed in 24.01.1.
As always, please find the changelog on GitHub.