From Quake Wiki
Quake is a 3D world, be sure to look up and down as you explore a level. Underwater areas are sometimes the only way to proceed, so go swimming when you have an opportunity.
Weapons and Combat
For tips on dealing with each of the monsters and bosses in Quake, see the Monsters page.
Main article: Trick Jumps
Trick Jumps are maneuvers that allow you to achieve a speed, height, or distance beyond what is usually possible with the physics of Quake. In general these 'features' were not intended by the designers at id Software, though there is some evidence that at least some of them were known to the designers during development. They are almost never necessary to progress through a level (with the exception of a few rare user-made levels), but can often be used to take a shortcut to another part of a level.