One thing I'd be wary of is having enemies hurt the player merely by touching him/her. A lot more fluid and dynamic moves can be pulled off, even in crowded areas, if the enemy has to actually attack the player for him to get hit/knocked back. Areas with semi-infinite swarms (of course, limiting how many are onscreen at once and using a delay so that they don't reappear immediately) which the player must wade through will also make the action more dynamic while forcing the player to push ahead at the same time. Viewtiful Joe or Gunstar Heroes would be great examples of what I'm talking about.

I'm actually contemplating a few similar ideas to make for an interesting combat system for the action-RPG I'm working on, using combo trees and such, though I'm using a 3/4 top-down view, so it won't be nearly to the extent you're going for. Still, I was thinking about putting together a multiplayer arena combat dealie to use in testing everything, and if it's fun, I might actually add it into the final project somewhere.

I was actually thinking of N when I made my last post. There's a game with style and fluidity. Give that little dude a sword and some throwing stars and a steady flow of robots, and it's game of the year time, baby!

Apparently, one of the common requests on the N forums is to give the poor ninja something to fight back with. Which would, of course, completely change the gameplay. But yeah, something with that level of fluidity and speed would be a good goal - any game that's fun to play and allows the player to show off is good in my book.

Of course that would wreck N, like giving your guy a bazooka in Lode Runner. But a game with similar style and flow, but add in a soldat-type mouse-aimed combat system (or a lock system, perhaps?) and some decent melee combos (preferably with some kind of slo-mo super-attacks and ragdoll animations) would be delightful.

Id just like to compare it to a D&D action adventure game, playing a mage for example at range. Many people use a single spell repeatedly, where as i prefer to mix them up in combinations that actually augment each other.

Certain vs racial bonuses, combined with some curse or damage modifing spell, or one that reduces a particular save type, it can make things far more intresting than just casting the most damaging or groovy looking spell.

Same is true for ranged combat i think, like in Fallout I/II, there were many ways you could hit your opponent (called shots and crits) as well as combinations of weapon types, ammunition types and stuff.

Its the subtle things that you dont notice immediatley, they are kind of abstracted from the beginner so as not to confuse them, but you learn and pick up on them the more you play and develop a style of your own. The more of them (hidden or subtle gameplay elements) there are the more variety of styles you can play and the greater the replayabillity.

Of course, hidden combos with animations and effects that dazzle can add to this.

That my personal oppinion.

There was a Japanese shoot-em-up where you gained additional points the closer you flew to bullets without actually getting hit by them.

Perhaps you could add something like that; extra bonus multipliers or damage or whatever, the closer you get to danger without actually getting hurt.

Yeah, like the "oncoming traffic" bonus and the "near miss" bonus in the Burnout games. If the guy shoots a three-shot spread at you and you go between the bullets instead of dodging them, you get a bonus based on how close together the bullets were and how fast they were going.