I'm honestly surprised by the comments. I've been treating this as a long time idle game that I return to. It is slow, but I am enjoying it a good deal.
One thing I'd like is for monsters in your inventory to have a little marker if they are essential to the next tribute. It's a pain to switch back and forth in the menus during a grind.
 "Idle Monster Frontier"){kind=icon}
 "Dozenbear"){kind=icon}