Funny that you mention this – the flyer mentions the electric fence so I already suspected that’s what I’d need to find to recharge the battery before I even got there! The puddle stumped me for a long time.
I think I was stuck on the puddle thing long enough that I wasn’t even thinking of it and the fence as the same puzzle. So much time was spent on that first part that once I cheated to find out how to finish it I thought of it as “puzzle accomplished!” and on to something else.
I think what makes that puzzle so hard, or at least it did for me, was that when you think about a radioactive liquid you associate it with the effects / transformative properties that it would possess and you try to find a related use for it.
I’m sure that if the game would have provided a can of paint instead of radioactive waste, I would have reached the solution more easily. I didn’t immediately consider the glowing liquid as a tool to mark the steps of people.
To be fair: Radioactivity can really be used for tracking (just maybe not in this glowing way) 