Report it to Scirra if offline mode doesn't work, reproduce it by switching off Internet router and such - I see others chime in that offline mode doesn't work, but I've been one of the lucky ones and it's always worked fine for me whenever my Internet went down.
Scirra have to think about pricing models and such, it's their full time jobs, they're likely weighing up different options and trying things to see what works for them - turns out the subscription system works for them. That's it, here we are. It's affordable to many but not all, but has excellent gains for the user if they did make a game that sold well.
The part that's more curious to discuss is the free version restrictions - that feels more important to focus on to foster growth and such.
Companies cannot kill piracy, otherwise that would have happened by now. It's much like anti-cheat, we have kernel-level anticheats, surely that is impossible for cheaters to beat? Nope, cheaters worked around this, whether running the game in a VM or using secondary hardware to work around this. The only current "true" anti-cheat/anti-piracy method is if it's even more cloud-based (i.e. Google Stadia, or NVIDIA GeForce Now).