First run through a game demo, I use an OC that can pretty much fit anywhere. She’s like a litmus test to see if I’ll like the game, but also to see how defined the MC is for the game.
Once I decide I want to play, then I start figuring out my MC. How that MC develops depends a great deal on how defined the game forces my MC to be.
For a game like I, the Forgotten One, where the MC’s history is well-defined, I will often go with one of the suggested names (for that one, it’s Kveta). For games where the player has more freedom, I go into super hunt mode of the perfect name… and when I say superhunt mode, I can take a long time to find the right name for a character. Once I have the name, I start figuring out how the character behaves, personality quirks, etc.
In games where the history isn’t defined (like Wayhaven), I develop the character’s history as I go along and see “who” they are. I get very in-depth with their histories, their reasoning, etc. Sometimes, that causes a disconnect in the game (like in Wayhaven, where the MCs are forced into feelings or forced into behaving a certain way, where it feels like they’re groveling at the RO’s feet), which results in fanfic if it becomes too bad.
I never play two different games with the same character. I do sometimes end up pulling a developed OC into my own writings that are unrelated to the game that “created” them. That’s only for the ones that are very well-defined by me, rather than the game having their history and personality set in stone.
As for appearance… that, honestly, just depends on my mood at the time. I’ve got blonds, brunettes, redheads, short haired, long haired, and everything in between. Ditto with skin and eye color.
When I create characters, I don’t really think about them in comparison to me since I don’t like self-inserting (I really wouldn’t fit well in most of these worlds and would flip off most ROs for being so damned wishy washy). So the creation is part whimsy, part vibe of the story/world, and part whether I want to be cooperative with the author or not (sometimes I’ll go contrary just because I don’t like being forced in one direction of play).
Fun question!