Welcome to the World Gen Mod!
It adds sixteen biomes (so far), five new random stones, a new dimension that only features the modded biomes, a new mob, and a new fluid, Oil.
New Biomes + New Dimension:
Dirty Plains - It's like the plains, but instead of Grass, you'll find lots of Podzol.
Fertile Desert - It's like a desert, but with more grass and trees. You'll find lots of donkeys here.
Arctic and Antarctic - Cold. Lots of polar bears in both.
Fungal Forest - Imagine a Mushroom Biome with more Mushroom.
Crimson Plains - Very very red. A new wood type lives here.
Obsidian Shards - A very rare biome that is filled with lava and Obsidian. Could be laggy, so stay away if your computer is weak.
Desert Mountains - Mountains in the desert, what more can I say?
Limestone Valley - A big valley filled with Limestone.
Flatlands - A very flat, grassy area. Great for building!
Deep Forest - Filled with lots of foliage. Hard to get through.
Mineral Mountain - A mountain filled with Shale and Gabbro.
Mega Mountain - A huge mountain. Goes up to the build limit.
The Pit - Dangerous.
Melted Antarctic - 99% Water and Fish.
Dirty Stone Mountains - It's like a mountain, but dirtier and shorter.
Extreme Dimension - A dimension with only the modded biomes in it. Good for looking at the mod!
New Blocks:
Chalk (Block) - Nice to look at. Mine it to get Chalk (Item)!
Chalk (Item) - Can be used to make Whitestone.
Mahogany Logs, Wood and Planks - A new, very red wood. Found in the Crimson Plains.
Gabbro - A hard rock that's found deep underground.
Tin Ore - Used to make Tin Foil (no uses yet,) and Tin tools.
Whitestone - Purely aesthetic. Can be polished and turned into bricks.
Shale - Made of lots of flat planes of rock. Useless for now.
Limestone - Strangely, more yellow than lime. Found mostly in the Limestone Valley
Oil Holder - Holds Oil. (Probably?)
Dirty Stone and Cobblestone - Stone and Cobblestone but dirty. Found in the Dirty Plains.
Slush - Slushy.
New Mob:
Pest - Silverfish but worse. Looks like Gabbro.
New Fluid:
Oil - Can be used as fuel.
Alpha 1.0.4 Changelog
+ Added Stone Chipper that turns Dirty Stone and Cobblestone into their clean variants.
+ Added Whitestone Brick Slabs, Stairs and Walls.
+ Added three new biomes, The Pit, Melted Antarctic, and the Dirty Stone Mountain
+ Added Slush block.
More Minecraft Mods
Would be nice to see more screenshots of the new biomes :)