Then it may have also just been that my server was overloaded. This is running on the weakest VPS I could find (officially with one CPU core, but I expect that it shares that) and some fixes I did to synchronize art display and output unexpectedly drove up the CPU load (not in a way I could debug during the jam). If more than a few dozen people started to test it at the same time, it could have just been overloaded. The code is pushing the schedulers of guile-fibers far outside their comfort zone with tons of microsleeps and I still need to tone that down a bit again. So that it recovered likely means that it wasn’t the network but just the combination of inefficient code-paths and the too weak server.
In the terminal you actually get blocky versions of the images, if you have catimg installed ☺
(but yes, the images look better in the browser: ./terras-heritage.w –server gets you that version running locally)
Thank you again for the report!