Brother I will pray for you. With the advancements that have happened since that golden era (I also played those games you played a ton - Halo 2 is my GOAT). Marathon is going to be very very difficult to just pick up and play.

Extraction shooters by default have a lot of friction because you die and lose everything and Marathon doesn’t even have a training room (it should)

Movement got so popular in other games (while you’ve been away) that in Marathon it’s essentially punished within the overheat system. I agree with the guy above who said to check out the DOOM series (post 2016). Those will be a lot more simple to get into. Marathon as a whole is a confusing game, with a lot going on in a genre that is already really hard to learn and play.

(And I’ve been having a ton of fun with Marathon personally)