Sometimes spuriously called a “civilian” identity (“superhero” is not a military rank!), the secret identity is a big part of a lot of superhero characters. Anyone can have one of these as long as they take some basic precautions to disguise themselves while they do their superheroing. It is the in-story reason for a heroic persona; a mask and a costume keep people from telling who you are in real life.
Changing into your costume is most often a matter of pulling off your normal clothes to reveal the colourful tights you’ve hidden underneath. As long as you’re wearing head-to-foot clothing—pants and long sleeves, for example—you can hide your costume. An Observe check (DC 25) can detect a costume under your clothes. For game purposes, we tend to just hand-wave away practical concerns like how this would make you a lot warmer than just wearing your street clothes, and where you store your boots. Pealing off your normal clothes to reveal your costume takes one round, assuming you leave your clothes where you change. Collecting your clothes and storing them, in a bag or case, takes another round. If you wear short sleeves and/or have uncovered legs—shorts or short skirts/dresses—you can still wear your tights rolled up your legs and arms, but they’re a little easier to detect (Observe DC 20).
You can also take off your street clothes and change into your tights, but that takes two rounds, plus a fourth to store you clothing, as described above. If your costume is anything more than tights—like a leather jacket or body armour—then you need to carry it in its own backpack or case. It’s always one round to get out of your street clothes. Changing into a different set of what are essentially street clothes, army pants and a leather jacket for example, is another round. Suites of actual body armour have donning times listed in them. Collecting your clothes still takes another round.
GMs are encouraged to play up the tension of costume changes as part of an exciting encounter, but also encouraged to not let taking an extra round to put on your boots become so pivotal that whole games are decided on that basis. It’s a balancing act between enforcing rules and creating satisfying storytelling.
Even with a mask, you can still potentially be recognized. Anyone who knows you knows your face, but also your build, your walk, and how you tend to stand. Covering your face helps, but there’s still a chance that they can tell who you are.
Recognising you requires an opposed test, Observe vs. Disguise/Performance (player’s choice). Remember, though, that only people who already know what you look like have a chance of recognizing you. If you lose your mask and a random bystander sees your face, they’ll just think you’re “some woman” or “some guy.”
The table, below, lists the equipment bonuses that various kinds of masks and costumes provide. This bonus applies to your Disguise/ Performance roll. Domino masks cover only the eyes, while half-masks cover either the lower or upper half of your face. Full-face masks cover your whole face. A hood, hat, or other device that covers your head can obscure your hair’s length and colour. Bulky clothing, like heavy leather or body armour as well as wrap-around capes and cloaks, hides your body’s shape. The equipment bonuses for masks stack with those of hoods/caps as well as bulky clothing, but bonuses from masks do not stack with each other, for obvious reasons.
The same mechanic applies if someone tries to recognise your voice, except that you can use only your Perform skill. In this case, coving your mouth with cloth or even just your hand muffles its sound enough that you get a +10 to your roll.
There are lots of ways you can disguise yourself and lots of ways you can get recognized, of course. Your GM will make all in-the-moment rulings under circumstances that these few paragraphs can’t cover.