[Proteus]

Originally Posted by Aagnathist

You're hitting very close to home with the Buck Rogers and Evernight examples

In what way? Is it that both involve folks "out of action" who return to find oppressive invaders in place? The trick then lies in making it reasonable for the invaders to take over while the heroes are absent. In Buck Rogers, it's because suspended animation glosses over the time passed. In Evernight, it's because the invaders have (literally) unearthly power and overwhelming force.

Originally Posted by Aagnathist

I'd like to make it a darker, gritty near-future experience, along the lines of The Walking Dead, without the zombies (dealing with people is challenging and dangerous enough as it is).

I confess I enjoy a bit of an unnatural element (fey, aliens, magic, psionics, superpowers, whatever) just because A) it can help paper over any odd bits in the setting's history or status that might otherwise hamper suspension of disbelief, and B) it lets players take advantage of the extra flexibility GURPS provides, producing more variety and wonder. It can also help attract players who want to try out the unusual.

Would The Morrow Project RPG (see Wikipedia) be another marker for what you have in mind? To put it briefly, U.S. soldiers placed in cryogenic suspension to protect against a fall of government find themselves awaking decades rather than days after the disaster, with much of their expected infrastructure absent or decayed, and have to discover the new world and their place within it.

Originally Posted by Aagnathist

OK, so we had one person wanting to focus mainly on the characters, no troop movements, but I would still like to add an additional element. What would y'all think of a survival element instead (along the lines of The Long Dark, if y'all are familiar with it)?

Play-by-post is SLOOOOOOOOOW. The more elements you add, the greater the danger of having the game bog down to falter or fail. Remember that every die-roll exchange is going to take a day or so; even if you get players to pre-describe and/or pre-roll combat actions (tactics, attacks, damage, defense rolls), combat will go by at about a second per day at best, and a short conversation to make a plan of action among the PCs can take half a week, more if it requires interaction with the GM about rolls or setting details.

Particularly if you're trying this medium out for the first time, I'd recommend starting simple and adding complexity later on; perhaps, for example, supplies are more plentiful and easier to come across early on, but become more difficult to acquire later on, thus adding resource management as a game component.