So, I've been playing around with making a modified version of Shadowrun. I've started with 4E's ruleset, and made the following significant changes:
1) Attributes maintain the exact same ratings that they have in 4E:
1-2 - weak
3-4 - human average
5-6 - human maximum
7+ - exceptional or metahuman
Your base dice pool for any action is always equal to your augmented Attribute rating. The only things that modify your dice pool are wound penalties and multiple action penalties.
2) Skills now go from 0 to 4:
0 - untrained (TN 6)
1 - novice (TN 5)
2 - professional (TN 4)
3 - expert (TN 3)
4 - world-class (TN 2)
Your target number (TN) for any action is always equal to 6 - your skill/specialty rating.
Thus, if you have an attribute of 4 and a skill level of 3, you roll 4 dice; each die that rolls 3 or higher is a 'hit'.
3) All tasks have a "Threshold". If you get no hits, you fail. If you get at least one hit, but don't make the threshold, you get a "minimal success". For attacks, this might be a grazing hit; for extended actions, this means you can keep going; for other actions, you don't succeed, but nothing bad happens either (or you can succeed with a glitch). If you get more hits than the threshold, you get a full success (full damage with a weapon, or completely succeed at your goal, or whatever). Additional hits augment your success.
Task modifiers modify the threshold for a task, but even if the threshold is reduced below 0, you still have to net at least one hit to succeed.
4) All 'natural' dice rolls use the "Rule of 6". Skillsofts, agents, and such don't use the Rule of 6, but all beings with Karma pools use the rule of 6 for all dice rolls involving their own Attributes and Skills.
5) "Initiative Passes" are replaced with an 'Action Point' system. All characters have an "attribute"-like score called 'Reflex'. Unaugmented characters have a Reflex of 1; things like Wired Reflexes, Synaptic Accelerators, etc. increase your Reflex. Characters who can enter VR or the Astral have multiple Reflex scores (one for each).
All characters have an "Action Pool" that holds a maximum of five action points (AP). When a character first joins a fight, they roll Reaction vs. a 5 (or vs. a 6 if they have Combat Paralysis); each hit grants them 1 AP. Complex actions cost 4 AP, simple actions cost 2 AP, free actions cost 1 AP. A character can 'rush' an action by halving their dice pool, rounded down (turning a complex action into a simple action, or a simple action into a free action).
Each 'beat' of combat lasts one second. During that second, the character with the most AP decides what to do and spends that many AP to do it. Then the next character, etc. Characters who don't have enough AP get to wait. At the end of the beat, each character gains a number of AP equal to their Reflex.