Sonic Ether's Unbelievable Shaders

Dynamic Shadows

Sonic Ether's Unbelievable Shaders is an unbelievable mod for Minecraft that improves the graphics of the game immensely. Keep in mind that you will need a computer with pretty decent specs to be able to run Minecraft with this mod installed. The mod adds things like dynamic shadows, waving wheat and tall grass, waving leaves and fire, coloured shadows and more. The difference between playing with this mod and without it is huge, and if your computer can handle it, it is definitely recommended. 

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Sonic Ether's Unbelievable Shaders

Extra Biomes

An icy Glacier biome.

Extra Biomes is a mod that adds 22 additional biomes to Minecraft. These extra biomes really help to spice up your world, espicially if you have grown tired of the same old biomes appearing over and over again.
Some examples of the biomes added are: Alps, Autumn Woods, Glacier, Ice Mountains, Rainforest, Woodlands and many more. Most of these biomes contain their own new trees and flowers, and a new terrain noise genration system is added for much more varied and epic terrain and caves.

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Extra Biomes

Optifine

Extreme Lag

For those of you that don't already have Optifine, this is a mod that is likely to change your minecraft experience. Optifine doesn't add any cool new creatures or block to your game, but what it does do is give your FPS a huge boost. Have you ever been bothered by a stuttering or laggy Minecraft? Well Optifine can help, it delivers huge boosts to your FPS, and even speeds up world loading. If you ever feel that your minecraft is running too slowly, I would definitely recommend this mod.

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Optifine

Explosives+

The damaged cause by a 'Mega Nuke'

Explosives+ is a Minecraft mod that adds many more explosives to the game. These include C4, Nukes, Hydrogen Bombs and Nova Bombs. It also adds other cool weapons like an elephant gun which destroys large sections of the landscape very quickly, a predator missile that you can call in from above and you can even mark a point for a stealth bomber to come in and destroy. This is an amazing and very thorough mod, and is definitely a recommended download.

Download:
Explosives+