Time-fuckery happens, and suddenly the game is plunged into a present day world, except that HYRDA took over during WW2. So they'd be past all the turmoil part of take over, but there would likely still be resistance. Cap might have been brainwashed to work for HYDRA, or else be a prisioner. You'd alter your history to fit it, but basically, if you are alive now you'd be alive there, even in you're not the sort HYDRA would like, so you have to figure it out. IDK, thoughts?