I wanted to reply to Leftly's post on this thread awhile ago but I haven't had the time for the proper responce and unfortuantly still don't. But without some level of predictability you can't come up with tactics/stratagies that work since by the nature of them you have to have some idea of the outcome that will occur. The game mechanics should be very predictable but the situations you are put into should not be.

That's just the thing, though -- tactics are by their nature techniques which must be invented in each individual situation, not techniques which must be applied to each individual situation. Someone can't win a war just by reading Sun Tzu's Art of War and being able to shoot a gun or swing a sword -- you need to be able to adapt to situations as they're presented. The tactic of throwing one enemy into another to bowl both off the edge of a cliff will not usually work twice. The real problem is that most games use hard-coded tactics, making combat just a matter of learning one tactic to forever be capable of defeating the same enemy again.

Granted, not everyone checks out every monster they meet, but if the way the game worked needed them to, and they liked the game, they'd certainly learn to do so.

The command interface and interactivity should always remain the same, but the actual world shouldn't be predictable (in my opinion, for this hypothetical game -- not for roguelikes) by any means. For example, whenever I drive, there are a billion things that could happen. That car that I'm watching on that side road could either drive out in front of me or wait in its lane. It could obstruct my view of a pedestrian. It could even get rear-ended and sent out into the street. No amount of training can make me react better to those situations -- it's intuition and coordination.