Considering that Construct 2 and the C2 runtime will not be supported next year, we will have no choice but using the C3 runtime. I chose to continue using C2 runtime because the "exported game won't work" alert could be disabled with it, but it still is not the case with the C3 runtime.
We are aware about the features that we will not be allowed to use when running the file:/// protocol.
But if these features are not important in our projects, it has to be possible to unblock it, as it was possible on Construct2. https://www.construct.net/en/forum/construct-2/how-do-i-18/remove-warning-quotexported-81632
What can I do now to run my html5 export when embedded on tablets ?