
A long level doesn't have to be physically long.

Make getting straight through to those areas obviously impossible - it's no fun being taunted by the exit that's blocked off by a ledge that's just a tiny bit too high to jump. It can help to reduce any unpleasant linearity in your maps. Let the player catch glimpses of where they are meant to be going. Why are things like this? What is the player doing? Make it look like something has happened, and give the player something to fight towards. Originally available on the VERC (but with some changes), it should be sufficiently general for most mappers interested by this difficult and often overlooked aspect of mapping.

This article sums up a list of useful hints and tips relating to single-player mapping, in no particular order.
