Skills:
Chemistry - Allows for the creation of complex potions and mixtures. (Unlocks Poison Mixing and w/ First Aid, Medicine Mixing.)
Metallurgy - Allows for the creation of gunpowder from mined sulphur. (Gunpowder lets you create TNT or bullets.)
Clockwork - (Remove day/night indicator.) Allows you to create watches, clocks, and unlocks gunsmithing.
Gunsmithing - Allows for the creation of simple guns such as flintlock pistols and rifles etc.
Biology - Allows you to study wildlife and diseases for combat bonuses and resistances.
Implement:
Weather - Rain, Snow, Lightning, Hail and natural disasters such as earthquakes, hurricanes, tornados etc.
Diseases - From the common cold to the plague.
Im pretty sure there have been posts regarding at least one of the above, but whatever. Im aware TNT will probably be used for griefing.