Yikes! That shouldn't be possible. Certainly can't repro it here. Pity you can't dump the memory on jsBeeb or I could load it up and take a peek.
I have some screenshots from level 13, showing the map with less sentries, plus another screenshot showing my score of 20100. The invisible sentries definitely exist, because I can hear them, plus the Danger!! message appears onscreen.
From your description, the most likely scenario is that their render IDs have been set to null, or maybe Explosion; in the latter case they wouldn't be invisible, just disguised as explosions, which you might not spot. Probably null. Can't see any way in code for that to happen short of random memory corruption.
I'll keep an eye out for it, but I'm not optimistic.
Statistics: Posted by dradford — Sat May 31, 2025 12:28 am