One of the great movements in design right now is contextual powers.
Assassin's Creed is a great example. A single player-command during combat (block + timed prevention strike = counterattack) can result in one of at least half-a-dozen moves. Which counterattack is seen depends on the relative position of defender-to-attacker and perhaps timing as well. Climbing is also contextual in Assassin's Creed. Simply direct Altair's movement and he'll use whatever actions are necessary to climb or leap that way. It's simple, fun, and occasionally surprising.
Fable 2 apparently makes spell-casting and ranged combat contextual as well. I'm anxious to see how that will work, but it also has me looking ahead to games of next year and beyond. How else might contextual powers be applied?
Game events are often activated by invisible triggers placed in the environment. When the player crosses a particular threshold or interacts with a particular object, a scripted event is set in motion. Triggers could also be used to activate variations in AI. When an AI character witnesses a particular event, crosses a particular threshold or such, then a change in personality occurs.
In Neverwinter Nights, child NPCs are invincible. If you attack one, the child will follow and attack your character relentlessly, eventually killing him. That's the closest thing I've seen to what I'm talking about, but that's still not it. That's basically a scripted event, a simple action command ("Kill the PC"). If it had been a change in AI, the children's perception of your character would change, but a number of subsequent events would be possible due to different personalities, different environmental circumstances, and other variables which combine on-the-fly.
I've long waited for contextual items. Item reward systems can be a lot of fun. I think they can be even more fun if some items are not what they appear to be, and if some items receive bonus powers in particular situations.
A broad item reward system has never been combined with a contextual combat system. It would be ridiculous to attempt as many attack animations as Assassin's Creed had for every weapon in a Diablo-type game. But breaking weapons down into a small number of classes (sword, axe, blunt, etc) would make this combo possible. In MMOs, it can be fun seeing how different characters' combat actions mix, but how much more so if there was significant variety within each character's optimal repertoire?
We've seen weapons and armor with effects or resistances that make them optimal for engagement with particular enemies. That's not the sort of contextual variety I'm praising here. In those cases, each item offers a single animation and three degrees of difficulty dependent on the enemy (ineffectual, average effect, superior effect). What I hope to see is different animations and other visible/audible effect variations independent of enemy type. Beyond mere show, I'm hoping for variety in type within one weapon.
When a player uses a "Frostbane" flaming sword against arctic inhabitants, he expects the sword to be more effectual and, though he might take some mild pleasure from pride in being smartly equipped, the experience is basically the same as using the weapon in any other scenario. On the other hand, imagine that the sword exhibits an effect type when fighting those arctic creatures that it doesn't exhibit elsewhere. What if the sword looked rather plain most of the time, but it glows hot as the player journeys further into the cold setting? What if fire suddenly erupted from the blade and was hurled at the enemy the blade was destined to fight?
Experiences like that don't just make players grin and think "cool...". Experiences like that make us wide-eyed, exhilirated, and we tell our friends about it days or even weeks later. It's more impressive, and it's feasible.
One of the cooler concepts I've ever read was something the Darkfall devs suggested about their Alfar race early in production (I don't know if the game still includes this scenario). The Alfar are ruled their god in physical form as a king, and that god is literally insane. All of their magic comes from him. So the spellcasters of that race have unpredictable magic. As the god's mood and sanity shift from one moment to the next, so does the potency of their spells. Sometimes their magic will sputter and fail, while at other times it is excessively powerful and brilliant.
While that's an extreme example, I think there's a lot of hope for similar variety within any particular skill. Variety can keep games fresh and replayable. It would be great if a skill gained early in a game could still surprise its user near the end.
How else might context be used to make games more fun?