Stellaris: Leviathans Story Pack Minimum System Requirements:
PC:
OS: Windows 7 x86 or newer
Processor: AMD Athlon II X4 640 at 3.0 Ghz / or Intel Core 2 Quad 9400 at 2.66 Ghz
Memory: 2 GB RAM
Graphics: AMD HD 5770 / or Nvidia GTX 460, with 1024MB VRAM. Latest available WHQL drivers from both manufacturers.
DirectX: Version 9.0c
Network: Broadband Internet connection
Storage: 4 GB available space
Additional Notes: Controller support: 3-button mouse, keyboard and speakers. Special multiplayer requirements: Internet Connection or LAN for multiplayer.

Mac:
OS: OS X 10.8.5 or newer
Processor: OS X 10.8.5 or newer
Memory: 4 GB RAM
Graphics: ATI Radeon HD 6750 / NVIDIA GeForce 320 or higher with 1024MB VRAM
Network: Broadband Internet connection
Storage: 4 GB available space
Additional Notes: Controller support: 3-button mouse, keyboard and speakers. Special multiplayer requirements: Internet Connection or LAN for multiplayer.

Linux:
OS: Ubuntu 14.04 x86
Processor: AMD Athlon II X4 640 at 3.0 Ghz / or Intel Core 2 Quad 9400 at 2.66 Ghz
Memory: 2 GB RAM
Graphics: AMD HD 5770 / or Nvidia GTX 460, with 1024MB VRAM. Latest available proprietary drivers from both manufacturers.
Network: Broadband Internet connection
Storage: 4 GB available space
Additional Notes: Controller support: 3-button mouse, keyboard and speakers. Special multiplayer requirements: Internet Connection or LAN for multiplayer.

Stellaris: Leviathans Story Pack Recommended System Requirements :
PC:
OS: Windows 7 x64 or newer
Processor: AMD Phenom II X4 850 at 3.3 Ghz or Intel i3 2100 at 3.1 Ghz
Memory: 4 GB RAM
Graphics: AMD HD 6850 or Nvidia GTX 560TI with 1024MB VRAM
Network: Broadband Internet connection
Storage: 4 GB available space

Mac:
OS: OS X 10.11 or newer
Processor: Intel Core i5 at 2.9Ghz
Memory: 4 GB RAM
Graphics: Nvidia GTX 750M or AMD R9 390M with 1024 VRAM
Network: Broadband Internet connection
Storage: 4 GB available space

Linux:
OS: Ubuntu 14.04 x64
Processor: AMD Phenom II X4 850 at 3.3 Ghz or Intel i3 2100 at 3.1 Ghz
Memory: 4 GB RAM
Graphics: AMD HD 6850 or Nvidia GTX 560TI with 1024MB VRAM
Network: Broadband Internet connection
Storage: 4 GB available space

Activation on Steam

1)      Download & install the Steam client on your computer from   here.

2)      Open the Steam client, register and login. Then, locate the Games tab on the top menu. Click that and select “Activate a Product on Steam..”

       

3)      Enter your code that is showed on the orders page of eTail. Market and and follow the steps showed to activate your game.

       

4)      The game can be monitored now and you can see it on the "Library" section on Steam. You can download and install the game now.

5)      If you need more information and support, you can click here: https://help.steampowered.com/en/wizard/HelpWithSteam