For stage 4 orb, I find the Freeze talent to be useful for taking out the last 2 enemies. Get both relatively low, then pause and freeze one just before you kill the other. When you can kill these over and over again without dying, you can leave the game running here and collect all the loot you want to dismantle in the forge.
Truncating the costs of items (rounding down) gives players the impression that they're able to purchase something and can lead to confusion when they think they have enough but are still unable to purchase the items. May I suggest rounding up and/or giving more significant figures? For example, 4.096 diamonds or even 4.1 diamonds would be a better representation of the cost required compared to 4 diamonds (rounded down).
The reward for the "Brutus Level 100" achievement isn't working properly. It's supposed to multiply both character and bot chop strength by 10, but it's only affecting the character and not the bots. Please fix this.
To add to my previous comment, you can skim the sides of a tunnel for only 1 energy as long as the line between the tip of the drill and the cursor does not pass through dirt, regardless of how long the tunnel is or what type of dirt it is. It's best done in a tunnel that's sloped downwards since the drill's tip would be closer to the dirt compared to upwards, but take care that the drill's tip is not actually in the dirt. The amount that is skimmed off the sides of the tunnel depends on how wide your drill can dig - upgrade it to drill wider.
The amount of energy consumed (and the distance the digging energy can travel) is determined by the amount and density of dirt between your drill and your cursor in a straight line. However, your drill digs some dirt along the sides of the path of the energy wave as well, so if you want to save energy, aim your cursor in the open space right next to the dirt you want to dig. If done right, you should consume only 1 energy for digging, since you're digging the "air" and not aiming directly at the dirt. This is best done when digging downwards at an angle of roughly 45 degrees, standing at the top of a tunnel and shaving off the sides. You can even consume 1 energy to dig a little bit at a time into hard rocks and dense dirt - remember to keep the cursor a few pixels away from the rock when aiming at the open space.
The same day that I reclaimed the last tile... "These guys calling themselves the Zombie Kill Squad showed up today armed to the teeth. After asking for some pointers they went out and offed zero of the Zed surrounding our fort. Nice guys!"
Survival mode is partially a matter of luck, because it's hard to tell which direction has fewer zombies. Most areas have zombies on two sides, forcing you to choose one direction to move in to start clearing. The most dangerous time is during the first reload, so if you manage to clear all the zombies on one side, you're pretty much safe for that wave. However, surviving wave 15 isn't so difficult if you move towards open space. This might seem counter-intuitive, but what it does is lure the zombies to the center so that you have space to strafe along the sides. This wouldn't work for higher waves when there are more zombies, but it's good enough to reach wave 15 and clear it for the hard badge.
The second level, Jupiter, is heavily reliant on luck. Many times two lines will cross each other with their red zones out of reach, making it impossible to go any further.
I noticed that the cave bosses dropped good gear and I was hoping that I could farm them for gear, so I didn't pick up the Hearthstone piece after killing the 2nd one. However, the boss never respawned and I got stuck because I couldn't complete the quest without the Hearthstone piece...
 "Frugal Knight"){kind=icon}
 "Death By Obsession"){kind=icon}
 "Three Goblets"){kind=icon}
 "Tales of Nebezem: Elemental Link Part 1"){kind=icon}
 "Press The Button"){kind=icon}
 "Idle Chopper"){kind=icon}
 "SHIFT 2"){kind=icon}
 "Talesworth Adventure: The Lost Artifacts"){kind=icon}
 "Topsy Turvy"){kind=icon}
 "Utopian Mining"){kind=icon}
 "Diggy"){kind=icon}
 "Rebuild"){kind=icon}
 "Pwong 2"){kind=icon}
 "How to Raise a Dragon"){kind=icon}
 "Reaper of the Undead"){kind=icon}
 "Beam Ball"){kind=icon}
 "Hands of War"){kind=icon}
 "Medieval Shorts 2"){kind=icon}
 "High Tea"){kind=icon}
Wow! That's wonderful!