No Caves! is a fairly small mod which lets you control most vanilla terrain features and entities. It doesn't let you fine-tune values, but simply say if certain features should exist or not.
Currently those features are:
Terrain and Structures
Caves
Ravines
End Cities (Only 1.12.2)
Mineshafts
Nether Bridges (Nether Fortress)
Nether Caves
Ocean Monuments
Villages
Woodland Mansions (Only 1.12.2)
Strongholds
Scattered Features
Witch Huts
Igloos
Desert Pyramids
Jungle Temples
Terrain Features
Lava
Lakes
Dungeons
Fires
Glowstone
Ice
Nether Lava
Nether Lava 2
Nether Magma
World Decoration (Version 1.2 and up)
Big Mushrooms
Cacti
Clay
Dead Bush
Desert Wells
Flowers
Fossils
Grass
Ice
Lava Lakes
Water Lakes
Lilypads
Pumpkins
Reeds/Sugarcanes
Rocks
Sand
Sand Pass 2
Mushrooms
Trees
Entities (Version 1.2 and up)
Skeletons
Zombies
Spiders
Blazes
Creepers
Endermen
Slime
Cave Spiders
Endermites
Ghasts
Giant Zombies
Guardians
Iron Golems
Magma Cubes
Pigmen
Polar Bears
Shulkers
Silverfish
Snowmen
Witches
Parrots (Only 1.12.2)
Wither Skeletons (Only 1.12.2 and 1.11.2)
Strays (Only 1.12.2 and 1.11.2)
Husks (Only 1.12.2 and 1.11.2)
Withers (Prevents them from spawning, not being created, resources will be lost)
Dragon (Prevents them from spawning, not being created, resources will be lost)
Villagers
Zombie Villagers (Only 1.12.2 and 1.11.2)
Horses
Donkeys (Only 1.12.2 and 1.11.2)
Mules (Only 1.12.2 and 1.11.2)
Wolves
Llamas (Only 1.12.2 and 1.11.2)
Evoker Fangs (Only 1.12.2 and 1.11.2)
Bats
Evokers (Only 1.12.2 and 1.11.2)
Vindicators (Only 1.12.2 and 1.11.2)
Illusion Illagers (Only 1.12.2)
Ocelots
Ender Crystals
Eggs
Rabbits
Pigs
Sheeps
Cows
Chickens
Squids
Skeleton Horses (Only 1.12.2 and 1.11.2)
Zombie Horses (Only 1.12.2 and 1.11.2)
Shulker Bullets
Dragon Fireballs
Elder Guardians (Only 1.12.2 and 1.11.2)
Fireballs
Small Fireballs
Large Fireballs
Snowballs
Arrows
Experience Orbs
Ender Eyes
Ender Pearls
Spectral Arrows
Mooshrooms
Potions
Experience Bottles
Item Frames
Primed TNT
Tipped Arrows
Planned Features
Ore spawn control in some form or another Completed. Will be released once other features are done.
Replace blocks in world, like Stone, Dirt or Grass with another block. About half done at the time of writing this
