Mutant
On Our Game
Mutants are social pariahs, which is not totally beyond understanding of even sympathetic humans in-game when many of them have dangerous powers. If they're obvious mutants, showing significant physical difference (blue skin, wings, etc.) little justification is needed. If they look normal and are publicly outed somehow, they are likely going to face the same discrimination along with having deceived people. It is difficult for people associated with many known super villains to everything from see a movie to get decent medical care. Many mutants are forced into separate communities. Please keep this in mind when applying for a mutant character.
Mutants can be divided into different classes:
Alpha
Alpha-level mutants have very powerful mutant abilities without any significant flaws. Less than ten percent of mutants fall into this classification. Alpha level mutants almost always have a normal human appearance and their mutation is powerful, useful and controllable. See: Professor Xavier or Magneto.
Beta
In terms of ability, beta-level mutants can be on par with alpha levels and will generally have a normal, human appearance, but while their mutation is powerful and useful, it is less controllable. Around ten percent of mutants are beta level. They can lead normal lives with minimal preparation. See: Cyclops (ruby-quartz glasses) or Wolverine (cannot avoid use of his healing factor).
Gamma
Gamma-level mutants have significant flaws with their powers or physical deformities. They are powerful, but their mutation is almost always uncontrollable and detrimental to living a normal life, even if it can be useful at times. See: Marrow or Rogue.
Delta & Epsilon-Delta
Delta-level mutants look entirely human and lack any significant flaws related to their mutation, but are much less powerful than all of the above. Deltas are the most common type of mutant, making up at least fifty percent of the population. If they have a normal human appearance, but their mutant powers are weaker or only narrowly applicable, though still controllable, the character is a delta level mutant.
A sub-class mutants, epsilon-delta mutants don't always manifest their powers; it can take moments of trauma, contact with someone else or another outside influence for their powers to activate, and then they may be out of control. They look entirely human. Epsilon-delta mutants might go their entire lives without ever learning they are mutants.
Epsilon
Epsilon mutants have the misfortune to combine the weakness of delta level mutants with the significant flaws of gamma level mutants. See: Beak pre-M-Day.
What We Want From Characters
Generally we're looking for gamma level mutants and below. It depends on the applicability of their powers on a street-level setting more so than how powerful they are, but both are factors. While the deciding factor is the "feel" of your final application, we would prefer little to no overlap with the other types of powers, as someone with a useful mutant ability would be less likely to seek technological or magical powers, already having natural abilities to rely on.
Magic
On Our Game
Magic is a difficult thing to tackle for a game of this nature. The liberty provided by the freeform system we use could leave magic an automatic trump card by way of versatility and lack of any natural resistances or counters. With this in mind, we have decided on a “functional” model for magic that fits within the Marvel universe. When Dr. Strange uses the Crimson Bands of Cytorrak, they're always the Crimson Bands; similar in effect and application. For an example better suited to the street-level nature of our game, if your character knows a spell to cause an object to burst into flames, using this to light cigarettes would be a bad idea. Burst into flames means “burst into flames”, not “fire does whatever is most helpful at this particular moment”. The amount of effort behind a spell is not necessarily consistent—an electric shock can stun, kill or just hurt—but the effect of “electric shock” is specific. New spells can take years, decades, even lifetimes to develop. Creative use of more antiquated sounding spells and terms is encouraged over “disable X-gene based abilities”.
We also ask that magic users give us a list of preferred techniques on the basis that magic is complicated and many things may need to be prepared well before use. This encourages specialization and balances magic with the standards we'll be requesting for mutant and technological powers. There should be a handful of abilities that they can use on the spot and optionally a few things that they know how to prepare when the need arises.
Potential drawbacks to magic characters come in the form of any of the malign supernatural beings such as Mephisto, Dormammu, Shuma Gorath or Chthon. There are any number of Old Ones, Outer Gods or apparent demons that can prey upon inexperienced magicians that dip into the more malicious end of the magical spectrum or tempt the good with something they desire.
What We Want From Characters
Magic being what it is, an opportunity for lots and lots of creativity, strong definitions are more difficult. We're not looking for characters that can immediately handle any situation, nor do we want vague execution with specificly helpful results. Magic should be a stepladder for overcoming obstacles, not a bulldozer.
[Editor's Note: If you want an example of what not to do, Runaways gives us Nico Minoru, who simply says whatever and even when the Staff of One's magic doesn't work right, it still handles the situation.]
Technology
On Our Game
Science “powers” should be specific in application and have, in some sense, a believable “comic book science” explanation. For example, Doctor Octopus can control his four mechanical arms because a laboratory accident caused an explosion which bombarded him with radiation. He could now control the arms, but was also left with personality-altering brain damage that left him a megalomaniac criminal. Knowing the specific chemicals or radiation does not really improve that in anyway and it's all bunk anyway, but it should be interesting bunk that can potentially be used as a story element.
Because, in theory, anyone of reasonable intelligence can operate a handful of well designed super-science gadgets (even smart people like things that are easy to use, presumably things would be designed as such), and they don't get the users ostracized from society like being a mutant or risk attracting the attention of nether worldly horrors as inexperienced magicians may, tech powers are constrained by budget and technical ability. If a character has technology-based “powers” and is self-sufficient, they will need a background and resources that, literally, fit the bill. Unemployed high school dropout builds their own power armor? Unlikely is an understatement. An example comes in Thunderbolts #113: Oliver Osnick, aka Steel Spider, is an example of a character lacking one of the two. He has the technical abilities, he ends up emptying his bank account and then some building and maintaining his equipment.
What We Want From Characters
Tech chararacters will likely be ordinary humans, barring technologically-inclined powers of another sort. They should have "comic-believable" ways to support their equipment, and said equipment should avoid being a Swiss army knife; having a gadget for every situation is less interesting than a creatively applied gadget meant for a different situation.