One of the larger changes introduced with Hack/Mine is the Area system. Areas consist of many chunks, randomly generated names, and random mob compositions. A dynamic atmosphere system was recently added as well.
Area generation is handled immediately after terrain is generated on a chunk-by-chunk basis. If an adjacent chunk has already been generated and has a "compatible" biome, the adjacent chunk's Area will grow into the current chunk. If no adjacent chunk has a growable Area, a new Area is created, with properties specific to the biome it contains.
An Area's name consists of a base name and a modifier (for example, "Hills" as the base and "Bloody" as the modifier results in "Bloody Hills.") The base is entirely dependent on the biome, while modifiers are only loosely dependent on the biome, additionally granting the Area special properties. The loose dependence on biomes is primarily to avoid silly names, like the "Gumdrop Inferno" (though it is unlike Frizzil to disallow such a thing.) Some areas have strange names like "Glitterying Plains". Sometimes it will even seem to be a pun, such as "Rock of Stars". Special properties currently include sky, fog, cloud, and overall screen color, as well as day and night lighting. Additionally, possible/required mobs to be spawned will be added shortly, with many more features planned.
In the future, there will be ways to "purify" an Area. For instance, defeating the neighborhood Lich would purge the Area of undead, or slaying the local Arch-demon would cleanse the lake of poison (Act Raiser anyone?) There is also talk of a "Base" mechanic, where rewards will be given for building a home in the more dangerous areas and keeping it intact for an extended period. This may also be a way to purify certain Areas.
Level of DifficultyEdit
The levels of difficulty are created when the map is generated
Spawn will aways be a level one area. Areas increment by one level depending on the adjacent area - for example, a level 4 area will be next to a level 3 area. Thus, you will not find a level 40 area next to a level 9 area, however some contributors suggest this is possible.
Idea of what is found in higher levelsEdit
Loot caps at level 40, and although it seems as though there is no point in venturing to higher level areas, there actually is. If your level is close to the level of the area, you should have no problem with killing the mobs because of the way the ability tree works now. If you are unsure, look at the Ability Tree page.
The reason you want to go to higher levels is because you can get much better loot modifiers in higher level places. At areas around level 50, you will rarely find semi "omni-gear", which is weak omni-gear that only give +20 boosts to 2 stats instead of 3. If you are unsure of what omni-gear is, look at the Equipment and Loot page. The higher level the area, the better loot you will get from the towers or dungeons, and you will get closer to achieving perfect items. There are guides on equipment and leveling in the respective Race pages.
Also, going to higher level areas as you yourself become stronger should be done because it is FUN. Staying in a level 60 area when you are level 80 makes everything really easy, and it becomes really boring as you aren't even exploring new areas and the mobs you are fighting are super easy.