Question Home Theater PC help

[BunnyK]

So I'm thinking of building a HTPC for a 4k tv, but i've only built one system so far, and it is my own personal rig. I have no experience in HTPC's and i was wondering what parts i would need to buy (and how much they cost) in order to be able to play 4k medium-low settings at 100 fps on games like Rocket League or Fall Guys.

Preferred budget is under $900 Canadian Dollars