I forgot about your comment on asking for the loading percentage, so wasn't paying enough attention to it. Do you have an option that can load the game without using the cache? Or can you tell me where the cache is stored, to manually clear it? The loading message was clear and it did show progress.
I initially tested on an older system (KUbuntu 20.04) and it failed to run. Here is the error:
[PYI-1904:ERROR] Failed to load Python shared library '/tmp/_MEIzPjGg3/libpython3.12.so.1.0': /lib/x86_64-linux-gnu/libm.so.6: version `GLIBC_2.38' not found (required by /tmp/_MEIzPjGg3/libpython3.12.so.1.0)
The game is a neat little simulator. Fun to mess around with.
I kept wanting to click on the materials to switch, though the scroll wheel does work well for quick switching once I got used to using it. A little thing, but I'd capitalize the names of the materials. It would also be nice if they had hover text with a brief description of what they do, like you have on the web page. The 3 "Life" materials also aren't clear in the menu and renaming them could help to clarify what thy are. The brush size bar isn't clear as to what it is initially. With experimentation it can become clearer, but you don't even see the "brush", only once you place something do you see the size changed. Adding a display for the brush size would help.