This simulator opens aimed straight up, so just pick a spot on the map and hit FIRE. The camera becomes the bullet: a 9 mm climbs to about 1.2 km, hangs weightless at the apex, then tumbles back down - the whole trip takes about 45 seconds and it lands at around 150 km/h. An AK-47 round makes it to roughly 2.3 km and takes a full minute. Wind drifts the falling bullet hundreds of metres, so it almost never lands where it started. You can watch all of it from the bullet's point of view over real 3D terrain.
Falling bullets are no joke: celebratory gunfire injures and kills people every year, because a bullet coming down at terminal velocity can still penetrate skin and bone. Never fire a real gun into the air. Here you can see exactly why, safely, in your browser.
Under the hood it is a point-mass exterior ballistics model: standard G1, G7 and sphere drag tables, the ICAO atmosphere (or live weather fetched at the firing point), wind, latitude-dependent gravity and RK4 integration at 240 Hz, checked against published range tables and Hatcher's falling-bullet measurements. 45 weapons from pistols, rifles and snipers to naval guns, mortars, trebuchets and the US Navy's 32 MJ electromagnetic railgun (a Mach 7 dart that flies about 200 km) - or build a custom gun where every parameter is a slider, up to 15 km/s. The atmosphere is the full US Standard Atmosphere to the edge of space and gravity falls off with altitude, so if your projectile keeps more than escape velocity (11.2 km/s) after punching through the air, it really does leave Earth and never comes back. Any elevation from 0 to 90 degrees, anywhere on Earth.