Video games are relatively limited in terms of freedom to react to in-game events. Even the best roleplaying computer games can only offer so much. Headcanon is when the player imagines story elements that are not inferred by the game itself, or that even directly contradict game events. It can be as simple as deciding your character's way of unwinding at the end of the adventure, or as deep and complex as how they felt the the first time they killed someone, and how that experience colours their response to violence now.
There's a link here to a Tumblr full of headcanons for the Mass Effect series. It does contain spoilers.
This is a pretty cool tool, both for writers and roleplayers, to help get into a character's head. Have any of you tried this? Or are there games you'd consider doing it with?
Here's my own list for my current Mass Effect run as a female Commander Shepard, Earthborn Sole Survivor for those who know the game, obvious spoilers below:
I'm currently in Mass Effect 2 and have just recruited the last of my team. Haven't yet started on the loyalty missions.
Shepard had a serious relationship with one of the marines in her squad. She watched him die on Akuze and swore she’d never have a relationship with a fellow officer again. Then she met Kaidan.
Anderson trained Shepard and has her CO for most of her military career. He’s the closest thing to a father she’s ever had.
Shepard never got over losing Kaidan.
Shepard is tired of surviving when so many people around her keep dying.
Shepard drinks to try and stop the nightmares about thresher maws. It doesn’t work.
Shepard can’t stand Ashley.
Shepard imagines she’d like a family, but has no idea what she’d do with one.
Despite growing up on Earth, Shepard loves being in space, exploring and learning.
Thane’s quiet demeanour and spirituality remind her of the lover she lost on Akuze. His spirituality, more than his looks, draw her to him.
Shepard sees Jack as a dark mirror of herself, a reminder of what she could become if she doesn’t control her temper and killing instincts.
Sometimes, Shepard enjoys the kill.
Shepard has a bit of a protective crush on Joker, but doesn’t think he’s interested. Joker doesn’t know, and thinks his disability would rule out any possibility of a relationship. He has loved her since she saved his life on the original Normandy.
Shepard thought fixing her scars from the Lazarus procedure would help. It didn’t.
Shepard has a fear of asphixiation following her death. She has nightmares about being unable to breathe and her face being covered. She hates EV work or missions on worlds where she has to wear her helmet. Similarly, she can't stand silence and plays music in her cabin even while she sleeps.