Pretty much what Panthera said.
Also I hate having to cross damage sectors in games. There's often protection from them (like radiation suits in Doom/Doom II) or in many RPGs there's magic to elevate you from the ground, but still. In the latter case it's just magic or items that you're having to expend for naught and in the former the map designer just forgets to give you a suit at all and it's just a bunch of guaranteed damage you're going to have to suffer.
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Essy, Avian Enthusiast