1.21 update. This version is considered beta because I'm experimenting with new ideas and there's a few things that don't work as intendend, but it's still playable.

• added 4 new beach biomes. 3 are independent from climate zones (based on geology instead i.e. erosion): Basalt Shore, Gravel Shore and Mud Shore. Red Sand Shore can instead be found near steep hot/arid zones
• added cave biome to shake up the underground: a default Caves biome right below the surface so that you can't tell where you are before getting out, with many different stone type variations independent from aboveground biomes, each with its own slightly different ore and monster generation. Then special caves that depend on different variables: Frozen Caves for arctic biomes, Prismarine Caves for ocean biomes, rarely Crystal Caves. Finally a Deep Caves biome for deeper areas, with better ores and no mineshafts.
• added another 2 biomes: Cold Swamp, to fill the missing swamps for cold low-humidity areas; and Frozen Plains, for extremely low temperature zones
• biomes and climate zones are now larger than vanilla but smaller than before, roughly a middle ground between default mode and large biomes mode
• slightly higher mountains and smoother terrain, with weird altitude changes still possible but not that common
• cave openings on the surface are much rarer to prevent that swiss cheese effect, but still not hard to find
• ore distribution is less forgiving: the best materials, including iron, are most often located deep underground, while near the surface only the worst ones are available
• larger beaches
• better distribution of highland biomes
• low terrain is now more likely to generate rivers, swamps and coasts
• brighter water colors for coasts
• Camels have a rare chance to generate in Windswept Plains so that finding them is a little less annoying (and it makes sense for them to spawn in steppe-like places)
• in general, new biomes feature different assortments of mobs, not always the same like vanilla does
• Mansion will now generate also in Pale Gardens and Oak Forests, to make them a little less annoying to find.
• fixed Igloo, Mineshafts, Ruined Portals, Trail Ruins and Trial Chambers not generating in new biomes
• fixed Villages not generating in some new biomes
• fixed Swamps not spawning Slimes and not having closer water fog
• fixed fire not burning out faster in jungles and swamps
• fixed Drowned not spawning more frequently in rivers
• fixed underwater music not playing in coasts and rivers
• fixed water ambient mobs not spawning less frequently in rivers
• fixed Ocean Monuments not checking for land in coasts and rivers
• fixed Snow Golems not melting in savannas
• fixed white Rabbits not spawning in snowy woodlands
• fixed warm and cold Frog variations not spawning in corresponding biomes
• fixed Strongholds not preferring land biomes and not generating in new biomes
• fixed rivers and swamps not being outlined on maps