Nightfall has a very simple route. No kills are necessary and there is no driving, except for a few seconds. There are a few grenade jumps, which can be seen in the IL record run.
The highlight of this level is a skip called the Forklift Skip. When you hear "negative, stick a remote detonator on it," head for the forklift and drive it to the gate that Jun would normally open. Align your forklift with the gate so that it is on your left side, you are parallel to the gate, and 6 is as close to where the gate opens as possible. If youre in the right spot when you get out, you should clip through the gate when you get out of the forklift. Once youve clipped, run to the end of the level, and you're done!