G&Z is a hardcore survival modpack offering lots of exploration (be careful) and PVE combat. I recommend bringing along a group of friends, as this can be extremely hard at times.

This modpack includes mods like:
First Aid - Minecraft Mods - CurseForge

First aid removes the normal minecraft health system and replaces it with a more in depth system. For example, your leg gets damaged, it may be harder for you to walk.

Dynamic Trees - Minecraft Mods - CurseForge

This mod adds better trees, ones with physics.

[FORGE] Simple Zombie Apocalypse - Minecraft Mods - CurseForge

This mod increases the spawn rate of the zombies.

The Lost Cities - Minecraft Mods - CurseForge

The Lost Cities adds a new world generation option, which spawns cities for the player to loot and explore.

Carry On - Minecraft Mods - CurseForge

Carry On allows the player to transport mobs, chests, etc by hand.

Modern Warfare Cubed - Minecraft Mods - CurseForge

MWC adds lots of weapons to the game, making defending yourself much easier.

And even more.

Gunz & Zombiez