I just realized that the level design in Dragon Marked For Death is more clever than I though.
I'm playing as a Shinobi, and there are locations I can't go to at the moment in some stages (for example, because they have obstacles I can't bypass). I thought I maybe needed some power-ups later in the game, or maybe I would get to explore that part of the maps in other missions (several missions take place in the same map, but in different parts of it).
The reality is, apparently only certain classes can go through there. Basically, by playing as a wall-jumping Shinobi, I'm reaching places, and using paths, other classes can't. But, those classes can use other paths I can't, because, say, the warrior can push and destroy certain walls, as other classes can with other obstacles.
So, by playing different classes, you'll get different paths available to you.
If you are playing co-op, with players using different classes, you and your buddies can, as a result, cover every nook and cranny of the map.
Speaking of Dragon Marked For Death, a reminder that the 20% launch discount ends tomorrow, and that the early buyer bonus DLC (which shouldn't be available to purchase in the future; at least INTI CREATES didn't make similar early buyer bonuses for other games available to purchase) ends on May 4th.