procedural generation - Why is permadeath essential to a roguelike design?

Roguelikes and roguelike-likes (Spelunky, The Binding of Isaac) tend to share a number of game design elements:

• Procedurally generated worlds


• Character growth by way of new abilities and powers



• Permanent death

I can understand why starting with permadeath as a premise would lead you to the other ideas: if you're going to be starting over a lot, you'll want variety in your experiences. But why do the first two elements imply a permadeath approach?

Answer

From a pragmatic standpoint..

If someone isn't going to be playing your game over and over again, but instead is going to play through once from start to end using checkpoints or free saves (like in most non-roguelikes), then why would you spend your time on implementing procedural generation for your world, instead of just making a single, static, well-balanced progression of maps?

I think the important concept is that if you're going to invest in procedural generation of your levels, then to get value from the procedurally generated levels, you really have to make someone want to play your game -- from the start of the procedurally generated content -- several times. And preferably, lots of times. Permadeath is one effective way to do that.

The Diablo games, on the other hand, accomplish this same goal by letting you start over again with your levelled-up character at a higher difficulty level, after winning. Their difficulty level scales up so that a single "playthrough" can wrap around the game several times, and so experiencing several variations of each level.

Lots of other games embed a repeatably-visitable procedurally built dungeon into a static, traditionally-created framing game (commonly an RPG of some sort. e.g.: Persona, Dark Cloud, Mystery Dungeon, etc). In this type of system, separate visits to a single dungeon generate different dungeon layouts. This also allows a single "playthrough" to wrap through your procedurally generated content several times.

These are both different game mechanics which achieve a similar net effect to permadeath, in terms of justifying the use of procedurally generated content.

Of course, permadeath makes more use of (and puts more pressure on) the procedural generation of your world than other approaches, since the user can easily wind up seeing variations on level 1 over and over and over again in close succession, if he dies and has to restart a lot. If your procedural generation of level 1 doesn't make the level unique enough to keep a player from getting bored with it after five or ten successive restarts, then maybe you should think about using a different mechanism to entice players into starting a new playthrough.