New Structures:

• Family Tree - found in most overworld biomes
• Alteration Site - found in most overworld biomes
• Angel Altar - found at peaks and mountain sides
• Great Body - found underground in most overworld biomes
• Heart Chamber - found underground in most overworld biomes
• Research Lab - rarely found underground in most overworld biomes
• Gorger Trap - found in most grassy and sandy overworld biomes as well as in the End

And more =]

New Mobs

In order from left to right:

• Gorger - found in Gorger Traps, it's a monster made up of a mouth and Gorger Guts - a block that acts as its body. It will kill anything that falls into its mouth and can only be killed by destroying the Gorger Guts
• Weaver - an insect capable of taking one's memory and weaving it into a physical bloody web. Causes Amnesia on hit
• Holder - a small critter that spawns near Risus structures. It will playfully sneak up on you to steal your held item and then run away with it laughing. Punching the Holder will result in it dropping the item
• Lover - a monster that will not attack the player. Instead it targets other creatures, turning them into Beloved versions. Whenever it transforms a mob, it will leave behind Spreading Remains. If you notice these appearing more and more in an area, that's a good indicator that you need to light it up.
• Ophanim - a stationary monster that will smite down all creatures that come close to it. Can only be killed with weaponry made from Concentration Cores.
• Hex - a Beloved Vex; it can no longer go through blocks but is in return more aggressive and causes the Bloodclogged effect on hit.
• Stalker - a Beloved Creeper; it will get as close as possible to the player, inflicting Darkness and Blindness.
• Singer - a Beloved Enderman; when it sees player it will start "singing", causing Nausea. It cannot walk around but it can still teleport.
• Licker - a Beloved Spider; its attacks will apply Pleasure, a much more lethal version of Poison that also makes controlling your movement difficult. On death, summons Baby Spiders.

New Pet

• Litter - an immortal pet, created through an Inhabiting Ritual. Whenever in a dark area, it will excrete a Light Dropping. Can be picked up and carried around. Also customizable.

New Weapons, Tools and Equipment

New Tools and Equipment:

• Skin Armor - offers less Armor points than Leather, but each piece increases Health by 5 (2.5 hearts)
• Sinner's Robe - offers a bit more Armor points than Skin, but less Health. Can be dyed and each piece can hold an Ability from a unique list that also changes its looks.
• Ophanim Wings - Elytra alternative, offering increased glide durability - but using fireworks or Riptide will deal a lot of damage to it.
• Diamond Tipped Ophanim Wings - it has an additional combat ability of stabbing enemies when crouching with it equipped.
• Eternal Youth - allows you to make pets immortal and forever babies
• Lucky and Wretched Charms - they give combat oriented benefits based on your luck attribute.
• Endless Pearl - a reuseable Ender Pearl; can store ten thousand of them as durability.
• Light Devourer - places Darkness.
• Hand of Greed - when in off-hand, increases block placement reach by 3.
• Threads Of The Firmament - a set of boots that gives several buffs related to speed and agility, for the cost of armor points and protective enchantments (a similar trade-off to what elytra vs chestplate is)
• Warhorn & Hexhorn - allows you to apply a potion effect in a range around you, either to allies or to enemies.

New Weapon Types:

• Boomstick - explodes on hit, damaging both the attacker and the victim. Destroys blocks.
• Flamethrower - spews fire that works even on Fire-resistant creatures.
• Egg Sac - can be thrown. Summons Baby Spiders on impact that attack everything.
• Knuckles - lower base damage than Swords, but faster attack speed, with an additional "Lunge" ability
• Heavy Axes - combat oriented Axes, accepting Sword Enchantments.
• Scythes - higher base damage than Swords, longer reach, but much lower attack speed.
• Greatswords - higher base damage than Swords, slightly longer reach, with much lower attack speed and slight speed reduction. Can launch a slash projectile.

New Enchantments

By throwing an enchanted item into an Alteration Catalyst, the Enchantments on it can turn into Execrations. These are more volatile versions of the original, either boosting the effect in return for a downside or purely flip it on its head. There are over 25 Execrations to be played with.

New Blocks

Risus adds a modest amount of blocks but most do have a function or mechanic. Tissue can decay into Bone; Skin can grow Hair; Zit pops; Remains can be smelted; Blood interacts with other liquids and can be dangerous as well, etc. Of particular note are:

• Depth Vase: a new storage container that can store between 1 to 81 stacks of items depending on how deep it is in the world. It has no UI but can be interacted with manually or with a Hopper to insert and extract items.
• Gorger Guts: a new storage container that has 54 slots and can pick up items in a 3x3 area above it.
• Alteration Catalyst: a new crafting medium; allows the conversion of certain vanilla items into Risus ones.
• Display Notches: they are a less intrusive alternative to Item Frames, allowing the display of items in various positions and rotations. The scale of flat items displayed matches that of blocks, meanwile 3D items (such as blocks) are at a one eighth (1:8) scale. These are also available as a separate mod for those who wish to use it without the Risus.
• Weaving Mechanism: capable of turning Experience Orbs into items that can store said experience.