I would set the game about 40 years before the main series. In Malkier the Kingdom in the borderlands that gets overran by the blight and Darkspawn. That gives a confined map area to work with and a dramatic event for the game to finish on. It's recent enough that there would be some easter egg characters to the main series. Young Jaim Farstrider could be a companion. You could help protect Baby Lan in his escape. Long lived Aes Sedei like Verin or Cadsuane could be floating about.

Your character would be an Aes Sedei. That means a cis woman (or trans man more later). That's going to really upset the Chuds, but I think that's the only way to work with the setting of having a magical user who also has the authority to go around doing missions and being present for historic events. You'd have a tutorial prologue in the White Tower wear you pass tests and choose your Ajah. The Ajah would give some different dialogue, stats bonuses and affect endings. It might affect romancing and bonding warders, though I think it would be also still good to be able to do whatever you want, just it would be in contradiction to your Ajah and therefore somewhat of a renegade. There'd also be a nationality you could pick but it just adds some dialogue and unlocks some hairstyles and jewellery.

Your companions would be either fighters to protect you at close range and between weaves (who if you get their affinity up you can bond as warders), or other One Power users to link with to enhance your powers. Most of those would be Aes Sedei (with maybe a surprise Black Ajah betrayal mixed in there), but I think a trans masc Saidar user who is a wilder (a self taught one power user) would be also a really cool companion who can also unlock your character realising they're trans if you want.

Then another main companion would be a trans woman who has used Saidin to transition themselves, channelling the opposite power they can give you an enormous power boost, but the taint on saidin means they are slowly dying and going mad. This character gets to basically look down the camera and call out the series for having "male" and "female" powers. Like "fuck you I'm a woman who channels Saidin deal with it". This character might have some sad endings (basically the only option for a Saidin user pre-cleanse), but if you work with them you unlock a bittersweet ending where your character "Stills" them with their consent (I chose here to use the feminine term, not the masculine "gentle") and bonds them as a warder so they survive the shock and subsequent depression. They live but also lose their magic (the only outcome that isn't derailing the book events).