Decisions = Challenge

This is part two of a thought. First read Dice ≠ Challenge for the groundwork of why challenging the players is important in RPGs, and why simply making them roll dice doesn't cut the mustard.

What challenges a player is forcing them to make hard decisions. There's multiple ways this can occur and two main categories such decisions fall into.

The first category is flavorful decisions. Do I work towards the group's goals, or strive at cross-purposes? Should I fight to the bitter end, or flee? Do I ask the hard questions, or let him off easy? Frontal assault, or sneak in under cover of night? The Lady, or the Tiger?
These are fun story-driven decisions, and the bigger the impact of the decision, the more fun it tends to generate. Deciding what your character had for lunch is only fun under specific narrow circumstances. Deciding how your character will confront the villain is almost always fun and exciting.

The second category is mechanical decisions. Here I'm mostly talking about Force Points, Luck Points, Drama Dice, Legendary Deeds, etc. These are resources a player can expend to influence die-rolls, or make events occur. Things like spells and powers (that can be used a number of times per day or per session) also fall into this category, though they are sort of a hybrid between the two. As with flavorful decisions, these mechanical ones generate more fun the bigger the impact the decision has on the game.

While almost all roleplaying scenarios allow for flavorful decisions, not all RPG systems incorporate mechanical decisions.

I prefer lighter rules-systems myself, but experience has shown me that most players get great enjoyment from mechanical decisions. The game that first opened my eyes to this was 7th Sea.