Personally, what i find the most annoying is the crafting chance. The way it's set up, they have you literally grind for days to have a chance to get pretty much anything useful.

Take the icon for example. That's 15 bugs and 10 torches. Best drop rate for torches is 25% on Stage 11, and Stage 9 has 80% bugs and 10% torches.

So, here goes:

Okay, we'll go for the bugs first. 15 bugs equals (15/0.8) 18,75, or 19 runs. Let's round up and say we get 2 torches along the way as well.

Next are the remaining torches. 8 of those, another (8/0.25) 32 runs. Total: 51 runs, for a total of 306 energy.

And THEN you get a 30% to actually get it, so that's an average of (306/0.3) 1.020 energy, or a player no-lifing it for 5.100 minutes, or 85 hours straight.

Yeeeaahhhh....