Survival Game: Games where the goal is to live as long as possible. Often (but not always), this involves plowing through ever increasing hordes of monsters until you eventually succumb to them.
Difficulty Levels: For the purposes of this article, anything that adjusts the difficulty of the game counts. This could take the form of skipping early levels, or making early levels harder.
Pure survival-based videogames were tremendously popular in the 1980’s arcade era: they practically were what people thought of when someone said “videogame.” They declined in the console era, but are resurgent these days; partly from the iOS gaming boom, and partly as game designers slowly realize the strengths of the framework. Survival games tend to be light on cruft, focusing not on more and more content but immediate and brutal challenge. While completion-based games often seem best suited for passive, cinematic gameplay, survival games focus instead on self-improvement in the face of ever-increasing challenge.
However, survival games have a key flaw best illustrated by analogy. Imagine an inept math teacher who only instructs through tests. He gives his student arithmetic tests to start. At first, the student fails the tests repeatedly. However, she slowly figures out the rules of arithmetic, and begins passing some of them. Whenever she passes an arithmetic test, the math teacher immediately gives her an algebra test, which she promptly fails. After she fails, the math teacher starts the loop over by giving her another arithmetic test.
Soon, she has mastered arithmetic and now routinely alternates between arithmetic tests (which she passes) and algebra tests (which she fails). Eventually, she masters algebra, and begins passing those tests as well. Her teacher rewards her with a new and exciting calculus test. She fails, of course, and soon she falls into a cycle of arithmetic tests (which hold very little value), algebra tests (which still hold some value, but not much), and calculus tests (which are what the student really should be working on).
At first, the style is reasonable, even optimal–test their skills until you find their limit, then go back to the basics and work your way up. However, as the student becomes more and more proficient at mathematics, the math teacher’s method becomes increasingly inefficient. By the time the student wants to learn graduate level mathematics (say, convergence of nonparametric regression techniques), her learning will be severely slowed by the remedial tests she has to grind through before she can even begin learning something new, let alone mastering high-level concepts she’s only seen a couple of times so far.
Survival games carry this exact flaw. As the player slowly masters the game, she progresses further and further on each playthrough. However, whenever she dies and starts over, she’ll have to start again at the exact same spot she did as a beginner. The early parts of the game inevitably become a grind as her skills trivialize their relatively low difficulty.
For this reason, survival strategy games need difficulty levels. The level of challenge appropriate for a beginner is far removed from that of an expert, but a survival game without difficulty levels ineptly presents the same challenges to both players. Without the ability to skip trivialized sections, your game is doomed to be abandoned — not because your player has mastered the game, but because her skills have advanced to the point where she no longer wants to play through increasingly long periods of trivial gameplay to get to a worthy challenge.