Universe Sandbox 2 accurate representation of gravity I've been playing Universe Sandbox for a while now and I have never been able to make a near Earth asteroid collide with it. By "make" I mean, simulating billions of years of known, near Earth objects until one of their orbits intersect. In this explanation Sir Cumference describes that Universe Sandbox 2 uses Newtonian physics to in its simulations. But wouldn't that calculate enough pull from Earth to slightly change the trajectory of the NEO to eventually impact?

We know, with almost 100% certainty that a LARGE NEO will impact Earth (probably sooner than later), otherwise why would we be investing so heavily on the Jet Propulsion Lab's Asteroid Watch program. 

Can the game not accurately simulate gravitational pull on those large scales or is there something else (probably a lot) I'm missing? Are all known NEOs not projected to have a relevant collision intersection with Earth?
A NEO only impacts Earth if both bodies are in the orbit intersection zone at the same time, closely enough for gravity $(F \propto 1/r^2)$ to bring them in contact.
In a simulation, the timestep should also be short enough to detect a collision.
An object at a moderate relative speed of 10 km/s crosses Earth's diameter in about 20 minutes; a longer timestep could turn a hit into a miss.

If you're already modeling real asteroids, try some which have hit Earth:
2008 TC3,
2014 AA,
2018 LA.
The short observation arcs make their pre-impact orbits highly uncertain, so a few small bodies spread within $\pm\sigma$ of each orbital element value may improve your chances.
Alternatively you could set an object up for immediate collision with Earth at a relative speed of 12 to 20 km/s in any direction, and run the simulator backward to see how it would get there.

The asteroid risk is real, but we should not overstate it.
If you visit JPL CNEOS Sentry and use unconstrained settings, it shows only a few objects with more than 1 chance in 1000 to hit Earth in the next 100 years, and most of those are small.
Few NEO orbits are known precisely enough to make meaningful predictions beyond that.
The Palermo scale quantifies a given object's threat to Earth in the foreseeable future.