Dwarves can easily get stuck.

[Solsund]

All you have to do to shut a brand new game down is accidently dig two blocks deep with all three digging dwarves. Because dwarves can only dig tiles one square away this means a dwarf can not do the essential upwards diagonal dig required to craft a makeshift staircase back out.

Your only options are not pretty. You can dig a small trench then have the game build a Wall in the pit for them to use as a stepping stone back out. That is assuming you have anything in your stockpile. If you don't then you have to dig a 3x3 area for a stockpile then try to build out using your builder, who is now stuck until it works.

If somehow you dig into a cave and fall more than one block down this is still theoretically possible but is tremendously difficult to do. I managed to make three steps up before my dwarves would refuse to go any higher despite the ceiling having empty space to jump into.

A lot of this could be solved by letting dwarves dig diagonally up, so long as the block above them is already missing. Then they could construct their own stairs without all the extra steps, assuming they don't refuse to climb as well.

[yueranyuan]

Yea I've noticed this kind of stuff. I agree that diagonal digging would be nice but aesthetically would it look odd?

Also, It is actually rather difficult to build stairs since it requires a fairly significant amount of micromanagement from the player. The only things that are painless to dig are cuboids.

Having the dwarf AI build stairs automatically is not really a solution - what if they destroy blocks they shouldn't destroy?

[Solsund]

I don't think a diagonal pick would look that bad considering they can already pick out a tile above their own head. It's one of the things that would need to be tried out and we can see how natural it feels.

When I said to "Have them build their own stairs" I more meant that a single miner dwarf could dig out of a hole without having to pull in a builder to build the stepping stones. I wasn't meaning true automation.

[mklingen]

This issue should be top priority. I've always played the game in 2D much like Dwarf Fortress -- mining one slice at a time. It seems most other people like to make Dwarves mine pits and other 3D structures, which is cool and should be supported.

Dwarves can actually mine any block that is 3 away at the moment (including diagonals). The behavior you see is a combination of a few factors:

1. Dwarves cannot climb walls (so they need to jump on top of blocks to get out)
2. Dwarf path planning tells them to go to any 6-way (manhattan) adjacent voxel before mining
3. Mining tasks are assigned using a greedy task allocation algorithm. This algorithm assigns the voxels top to bottom nearest to furthest.

The result is that if you tell the dwarf to dig downwards he may get stuck in a situation where mining a block causes him to fall into a pit that is more than 2 deep. From there it may be impossible to get to a 6-way adjacent voxel to mine the next block, resulting in failure. The inverse problem exists when trying to build towers.

Ways that this can be fixed:

• Only allow the player to mine vertically when pressing ALT. This means they are less likely to accidentally tell the dwarf to mine out a huge vertical pit.
• When mining vertically, automatically insert a staircase along one or more edges of the pit. The player must then micromanage dwarves to remove the staircase if they really want to.
• Allow dwarves to climb walls when all hope is lost. (This is something I implemented in one of the change sets I reverted because of Resharper silliness)
• Fix the path planning so that dwarves can plan to any location that is 3 away from the block they want to mine, rather than just 6-adjacent cells.
• Fix task allocation so that it doesn't get dwarves into a stuck-in-a-pit situation.
• Fix the "dwarves falling off of things" problem and force dwarves to jump to the nearest voxel that is available before falling.

[yueranyuan]

Re: Matt's solutions.

• Alt I like this method because making it harder to create different vertical cuboid holes will make the layer slicing a lot less painful since there will presumably be fewer layers to worry about
• Staircase This would solve some situations but then we'd have to fix staircase-only problems e.g. what happens if the voxel around the staircase are destroyed? what happens if we build a wall on top of the staircase, etc. The dwarves would still be stuck.
• Climb This is nice because it's short and simple, but renders walls kind of useless as defense structures for enemies etc. Not sure if enemy fortresses are in the cards.
• Task allocation This sounds like it could have uncaught edge cases but would it would be nice in general to make the task manager smarter. I'm guessing what we can do is just drop the dwarf into the center of a designatedVoxel cuboid and see if we can plan back to the home base. We'd have to introduce "hypothetical" missing voxels to the AStar planner.
• Jump to Nearest Correct me if I'm wrong but that sounds like a solution to a related but separate problem

[mklingen]

I have alleviated some of these issues in the past few commits. For example, https://github.com/CompletelyFairGames/dwarfcorp/commit/1fbea99bfd77c1c868294e7065b96b4a3dd0309d makes it impossible to select invisible voxels unless the player explicitly presses a key. I have also made it possible for dwarves to climb out of danger when needed. Next I will fix the planner so that dwarves can plan to a block that is 26 adjacent rather than just 6 adjacent.