Non-linear difficulty

Effectively this means that you can encounter the most difficult challenges early on and the weakest won't just "disappear" to make room for the harder ones. Often compounded with alternate solutions, such as simply running away or avoiding the harder ones, though if the avoidance is the only option you have, then this doesn't really count (there's no sudden rise in difficulty as the difficult obstacle can't be encountered).

Boss battles and similar should be ignored for this, as they're naturally much more difficult than anything surrounding them (they wouldn't be boss battles otherwise).