Bug Update.
For some reason the last minion in my list is never the same when I leave the game and replay it. I upgrade the last one in the list to say 100 seconds / 10 bones. But despite saving my progress several times after during a 1 minute period, for some reason the minion resets. sometimes all the way back to 120 seconds / 1 bone. The others seem fine, its just that last one.
Also, your bonus multiplier. it goes up to 3x but it gives the impression it multiplies by 3. it actually does 3+ so only adds three.
eventually I will do an update video, I will see how it goes.