tl;dr: More ores, things to craft, two new dimensions, more weapons and armor, better caves, better biomes, more mobs, etc. Minecraft, but better without the bloat of most other modpacks worth playing.

This pack has 37 primary mods and is meant to run great on a 6GB server. It has, what I believe to be, the bare minimum to achieve the "modded minecraft" experience.

There are also 13 dependency mods, which are required for some primary mods to function correctly. So technically, there are 50 mods in this pack.

Included is also the Sildurs High shaders pack. You will just need to add optifine before you can select it. Directions are below.

This is the client side pack. It currently runs great and exactly as it should, but new versions may roll out with tweaked config files.

Server side pack will be uploaded soon.

Here's a list of mods categorized by what they improve:

Additional Dimensions

Twilight Forest

The Aether

Additional Ores/Crafting/Mobs

Actually Additions

Better Animals Plus

Baubles

Botania

Dragon Mounts 2

Enhanced Mob Spawners

Tinker's Construct

Improved World

Biomes O' Plenty

Whorly's Caves (custom config - slightly more caves poking through to the surface, larger interior, fewer vertical drops)

Fast Leaf Decay

Gravestone Mod

JourneyMap

Large Ore Deposits

Quark (non-skittish stonelings for easier Heart of Diamonds)

Save My Stronghold! (So Worley's Caves doesn't delete strongholds)

Tumbleweed

Improved Farming

Bonsai Trees 2

Forestry

Ore Excavation (tinker upgrade/enchant required)

Improved Storage

Ender Storage

Iron Backpacks

Iron Chests

Refined Storage

Storage Drawers

Improved Stuff

Baubles

JEI

Simply Jetpacks 2

Tinker's Tool Leveling

Tool Progression

Improved Client Side

Hwyla

JEI

Mouse Tweaks

Sound Filters

And if you don't want them categorized, here they are alphabetized:

Actually Additions

Actually Baubles

Aether: Lost Continent

Baubles

Better Animals Plus

Biomes O' Plenty

Bonsai Trees 2

Botania

ConnectedTexturesMod (currently no texture mods applied)

Dragon Mounts 2

Ender Storage 1.8

Enhanced Mob Spawners

Fast Leaf Decay

Forestry

Gravestone Mod

Hwyla

Iron Backpacks

Iron Chests

JourneyMap

Just Enough Items (JEI)

Large Ore Deposits

Mouse Tweaks

Ore Excavation

Ore Excavation Integration

Quark

Refined Storage

Save My Stronghold!

Simply Jetpacks 2

Sound Filters

Storage Drawers

The Twilight Forest

Tinker's Aether

Tinkers Construct

Tinkers' Tool Leveling

Tool Progression

Tumbleweed

VanillaFix

Worley's Caves

Adding Optifine

Download here: OptiFine_1.12.2_HD_U_F5

Make sure you select KEEP once it finishes downloading.

Open Twitch and go to Mods > Minecraft > Aquarius7373 > Settings icon at top right > Open Folder > Mods

Drag the newly downloaded Optifine.jar into your mods folder. Done!

Optional: Increase RAM Allowance, 1a)

Download 64 bit java here: Java Versions

Select Windows Offline (64-bit). Finish installation before launching Minecraft. This will allow you to allocate more than 1GB ram to minecraft.

Now play the Aquarius7373 modpack from Twitch.

Optional: Increase RAM Allowance, 1b)

Once the Minecraft launcher opens, click Installations > Click 3 dots to right of Aquarius7373 > Edit > More Options

Change -Xmx3228m to a larger number. This means it'll let the game use about 3GB. I set mine to 10228 for 10GB but it depends on how much you have to spare. I have 32GB ram total.

Inside the Minecraft main menu, go:

Options > Video Settings > Shaders > Click Sildurs. Game will seem like it freezes for a little while. Just let it do its thing. Once the shader is selected, click Done.

Now when you play it'll look amazing!