For $800+ you can build a computer that will be optimized for gaming, which that one is not.
If you want to post a budget and what extras you'll need (keyboard/mouse/monitor) I'm sure the community can cook you up something nice.
If you want some insight into building your own check out:
Build a PC - Introduction to Building your PC - PCitYourself.com
and/or, if you have 45min to watch a video:
*Edit - Ninjas, all of you
Please read through the thread thoroughly before responding.
Nobody wants to read a wall of text, formatting is your friend.
i5 3570k | 8GB G.Skill 1600MHz | R9 290 | SeaSonic 750X