The core of the system is simple: You start with a specified number of PP (which can stand for Power Points or Perk Points as desired), which can be spent on powers or perks, which there isn't really a solid line between. You can also take disadvantages for more PP.
The limits on PP and disadvantages will vary with the power level of the created character (and PP may be awarded in addition to normal XP); however, a good number would probably be 100 PP and a 50-point disadvantage cap. A typical GURPS character would tend to have at least 200-300 points, but they buy Attributes and Skills, which we probably won't be. If we stick to 100 we avoid getting out-of-control. The disadvantage cap should probably be no more than 50% of the base PP total.
Advantages
For the most part, these are simple; pay the price, you get the advantage. Specific exceptions are noted towards the bottom.
GURPS Perks
GURPS's Perks are minor bonuses your character has, paying one point for each. The same applies here: Pay one PP and you can get, for instance, immunity to hangovers or a built-in vacuum cleaner. (Hey, you get what you pay for.)
You might be able to get such things for free, if they're integral to your character concept. Ask the GM and other players.
Disadvantages
Ditto. Generally, though, if there's not an obvious downside (e.g, with Disturbing Voice), you need to check with the GM and other players before getting PP for it.
Quirks
In GURPS, quirks are 1-point disadvantages that everyone's limited to having five of. In this system, you are heavily discouraged from taking them for PP unless you're willing to have them impact the game. Cannot Float is probably okay, but Dislikes and Staid less so. If you're uncertain, ask the GM and players for their input.
Spells
GURPS spells don't really fit into the currently-proposed system, so unless for some reason they're vital to your character don't bother. If they are, I'm willing to look over things on a case-by-case basis. Chances are that only one or two spells which don't have similar advantages are needed.
Skills
Skills also don't fit well into the currently-proposed system, for roughly the same reason. However, Talents are an Advantage. Purchasing a level of Talent gives you +1 Skill for rolls with the associated skills. Yes, this is more significant than the bonuses to skill levels from the Talent advantage do in GURPS, but in GURPs said advantage also gives you bonuses to Reaction rolls and reductions in the time to learn skills, which don't apply to RMG-3.0. Overall, it's reasonably balanced.
Stats
If you don't have enough supernatural or otherwise interesting abilities to use your PP, you can increase stats. I suggest a value of 15 PP per point of Stat. Why?
1. Attributes in GURPS cost either 10 points (ST, HT) or 20 (DX, IQ).
2. The advantages of DX and IQ are broken up into multiple Stats. Thus, we can act as though Attributes cost about 10 character points per attribute point.
3. Attributes provide advantages not covered by the stats. For instance, ST increases hit points, while HT increases fatigue points. Overall, this decreases their value by a guesstimated 25% to 7.5 (based in large part on HP and FP, the clearest examples of not-covered-by-the-equivalent-Stat).
4. An average human's Attributes are 10 each, but their Stats are 5 each. Thus, double the 7.5 to get 15.
Again, while not perfect, it will suffice.
Damage Types
How do we translate damage from Innate Attacks and such into damage in your system? That's a tricky one. It would be fairly easy to make a conversion factor for each damage type, but that wouldn't work too nicely with the existing system, now would it?
Let's start with Strikers, Teeth, and other natural melee weapons granted by Advantages. Teeth and most Claws can be treated as Normal weapons, but Strikers, the bigger Claws, or possibly a combination of weaker weapons may qualify as Good weapons.
More mundane Innate Attacks, like an implanted firearm or acid spit, can be treated similarly. A weapon which functions as an Unarmed attack would only cost a few points (let's say 3); 10 points would get you a Normal weapon; 20 a Good one; more powerful mundane Innate Attacks would be available on request.
"Default" magical attacks should probably cost something like 15 points, or only 5 if for some reason it's melee-range. If you want to enhance it further, you can either buy bonus damage (doubling for each "quality level") or apply Modifiers.
Non-damaging attacks like Afflictions are...tricky and will be evaluated on a case-by-case basis, trying to capture the essence of the effect while keeping it balanced in the new rules.
This is the section I have the least confidence in; I'm mostly taking the simple stuff at the beginning and trying to extrapolate for the rest. Please comment if you think you have a better solution!
Alternate Forms
Covered by the Alternate Form advantage. Basically, as long as the PP total of traits the alternate form has that the normal one does not exceed the PP total of the inverse, it costs 15 PP. (Stats can be rearranged freely; a -1 to Skill balances a +1 to Strength, for instance.)
Gadgets
Teh ability to make new gadgets would fall under Gadgeteering. Specific special gadgets which come up regularly and have significant impact should be bought as advantages, albeit with special Gadget Limitations listed on pages 116-117 which can easily reduce cost by half, and potentially down to the 20% minimum cost GURPS imposes (and which will probably be enforced here if it ever comes up, especially if someone's trying to by an Advantage for free).
Audience Input
You've probably noticed that at times, I've asked for the input of the GM and players. Doesn't this negate the advantages of the system, you ask? Not at all.
First off, all other proposed systems require this to some extent. More importantly, this system only requires such input when people are trying to extract as much power as they can from the system. Non-min-maxers should be content with not doing so in any significant way, and so won't need much oversight; min-maxers should be obvious enough, and so can be shot down quickly. This system requires less and (usually) easier audits. Assuming, of course, that people follow them.
Alright. That should be everything. Any questions?
Indeed. I knew what you meant, and created such. (If I thought you wanted a whole system, I would have snarkily pointed to the GURPS rulebook.)
You're conveniently ignoring that people have been complaining about it for ages. I know I've levied complaints against it in the past, you revisionist weirdo.
Balance.
Then nerf it. I'm willing to draw up stats for Kyle under my GURPS hybrid, which should be more balanced at least.