Btw, I tried to make him explore again, and the time went up to 1016 days. Then when I recall him once more, the times goes back to 508 days and so on.
I guess I'll let him die there, which is unfortunate. I hope it won't happen again...
Just curious, did you mess with your phone's time settings? I did that and that affected my game, including the explorers by extending the amount of time for them to return. It wasn't as long as yours, about a week for mine. If you didn't, then hopefully the devs get back to you.
No I didn't touch anything there, I didn't remove the battery nor change the time settings. I actually never turn off the phone, I just charge it when needed and I always close the game properly by returning to the main menu first and then using the back button to quit.
Thanks for your input anyway