Please rate my system!

Seems pretty good to me, sure you don't want an ATX board? The B450 Pro4 is actually cheaper than the B450M Pro4, at least last I checked.

Another thing - the 1060 will not run all games at ultra settings, you'll have to turn it down to high in many modern demanding games.
 
it looks good.
But there are some better choices to be had that save you money in certain areas in order to increase budget in others.

You can download and install and use Windows 10 completely free with just a small watermark in the corner and can activate it later on when you get the money.
Can either activate by buying the $100 version or by getting an activation key from somewhere online for less. Your choice.

PCPartPicker part list / Price breakdown by merchant

CPU: AMD - Ryzen 5 2600 3.4 GHz 6-Core Processor ($160.98 @ Newegg)
Motherboard: ASRock - B450 Pro4 ATX AM4 Motherboard ($74.99 @ Newegg)
Memory: Team - Vulcan 16 GB (2 x 8 GB) DDR4-3000 Memory ($99.99 @ Newegg)
Storage: Crucial - MX500 250 GB 2.5" Solid State Drive ($42.99 @ Adorama)
Storage: Seagate - Barracuda 2 TB 3.5" 7200RPM Internal Hard Drive ($58.89 @ OutletPC)
Video Card: EVGA - GeForce GTX 1070 8 GB FTW Gaming ACX 3.0 Video Card ($329.99 @ Newegg)
Case: Fractal Design - Focus G (Black) ATX Mid Tower Case ($59.97 @ Newegg)
Power Supply: EVGA - SuperNOVA G3 650 W 80+ Gold Certified Fully-Modular ATX Power Supply ($49.99 @ Newegg)
Total: $877.79
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2018-11-23 23:09 EST-0500