This mod makes hardcore worlds (by default) harder without introducing new entities, or items. This mod is not a core mod!
Specifically, the features of this mod are the following category: Mining, Reworked Fortune, Reworked Health Regeneration, Disabled Natural Regeneration in newly created hardcore worlds, much more frequent thunderstorms and rain, food values and saturation values modified (works for modded items as long as it extends ItemFood in its code), all mobs deal more damage and take less damage if the source of the damage is a player, player-targeted lightning strikes are now a thing, and additional exhaustion. Moreover, having a low hunger will punish the player with nasty status effects. This mod is very configurable.
You can no longer mine if you don't hold any tool that is capable of mining (Is designed to work with modded tools such as tinker's construct.)
This is also very configurable.
Enabled by default, the power of fortune is not always reliably at its level (for example, it can work as if its a level 1 or 2 despite the enchantment level of the used tool is 4 or 3).
Regeneration is now very nerfed. Having a wither status effect will slow down your health regeneration, being very hungry (food bar at 1 or 0) will disable the player from being healed (unless an another mod that does the healing does not fire healing event), adds additional independent-from-vanilla exhaust every time you heal regardless of how you actually are healed and requires the status effect vanilla regeneration (its healing ability is not removed) in order for the healing mechanic to be effective (An example of it would be drinking instant health potions in vanilla. This is not necessarily just from a status effect). Note: The idea of having regeneration as a means in order for your healing ability to return to normal started as a question that is, how absurdly hassle is it to kill a ghast only for their ghast tears to fall into the pit of lava?
Disabled Natural Regeneration In Newly Created Hardcore Worlds:
Pretty Self Explanatory (Configurable but in older worlds, you'd have to disable the gamerule naturalRegeneration manually, sorry).
Frequent Thunderstorms and Rain:
In addition to vanilla rolls, increased the world's frequency to rain or thunder. Dangerous if its thunderstorms as you will constantly be handling entities without regeneration and to add an insult to an injury, lightning strikes that want you dead if default settings are used. (Configurable)
Food and Saturation Values:
By default (Configurable), halves the received food and saturation values.
By default (Configurable), players are subjected to a certain amount of exhaust independent from vanilla even if he/she does not do anything at all. Hunger's ability to add exhaust is also strengthened by default.
Negative Status Effects When Food Bar is Low:
Players who are hungry will occasionally (configurable) be inflicted with a negative status effect.
This/These status effect/s grow/s stronger and additional are introduced the lower the food bar is.
Player-Targeted Lightning Strikes:
By default (Configurable), there is a 1% chance per second that an open sky exposed player will be struck by a lightning if the weather is thunder.
Stronger and Resilient Mobs Against Players:
By default (Configurable), Mobs deal more damage (without changing attributes, 1.5x) and takes less damage (0.65x the normal damage) against player dealt damage.
Hardcore Drowning and Swimming, Hardcore Lava, Hardcore Nether, Hardcore End and etc.
I also consider suggestions as long as it fits the mod's theme.