my ideal rpg is a tactical cyberpunk x-com roguelike which also randomizes story and characters due to modular design of both, and is about cops fighting off the just starting zombie apocalypse, and ultimately failing.
it would start with some regular assignments (domestic abuse, crazy druggies, cyborg running amok, corporate espionage, gang wars, violent human rights riots and all that) that feature plenty of c&c, a stage that would set the basic attitudes of the other cops towards you, based on whom you decide to rat out for what, who dies because of your incompetence, and so on. then those assignments would become increasingly bizarre, violent, and gorey, all the while your unit would receive less and less funding, shittier equipment, and go down the drain.
that first phase of the game (tutorial essentially, but much extensive than one would normally be) would culminate in your unit being dissolved, and you deciding to go private/corporate, with a selection somewhat based on choices, contacts, and evidence you made and uncovered. the attitudes of other cops from your unit would determine who'd come with you, and your reputation how much other personnel you could snatch away, or maybe even "requisition" some equipment.
the proper gamephase would feature you on a x-com style map of the megacity with surrounding suburbs and industry areas that graphically reflects the level of contamination and possibly a representation of the swarm at later stages. missions would be assignments from clients/mr johnson with different side objective based on your chosen affiliation. corporates could want you to destroy evidence linking them to the outbreak, the military could want said evidence and data to get ahead of corps in their research, crazy eccentrics would want "live" zombies for sexgames...
as the contamination would progress, so would your mission focus and your mechanics of acquiring missions shift. eventually, you would start sending scouting parties to acquire intel on possible missions, rescue key personnel that might hold information on anything that would allow you to hold out longer (allowing various approaches to interrogation from asking nicely and letting them stay at your base to torture and throwing them off the roof), or just get information on enemies inside missions, which would make them partially static (say, you know there are so and so many zombies gathering in three groups in your target area, the location of those groups, the number of immediate reinforcements, and how big of a window you have before the bulk of the swarm arrives and eradicates your team).
eventually, you would notice small swarms forming on the strategic map, flowing around the place, clustering together.. slowly following your vehicles or making their way to mission areas. you'd also notice that traveling through the swarm costs your team an increased amount of resources at the very least, and possibly even the whole team, and that missions inside swarmed areas have an insane amount of zombies in them, that makes them nearly impossible to accomplish. at this point you would develop sonic repellents and baits to somewhat influence the swarm, allowing you to spend resources to clear a mission area before entering it, if it contains something you really really want, but the swarms would be less influenced with size, and eventually it would all culminate in one giant swarm anyway, which is when the endgame begins.
the swarm noticeably starts making its way towards your hq. slowly. you can still clear holes in it just long enough for mission vehicles to arrive and allow you to snatch some resources, but eventually it will reach your hq, at which point the siege begins.
when sieged, costs of travel through the swarm rise dramatically, pretty much wiping entire teams if they aren't incredibly overpowered and flooding everything in hot lead. you can still do missions, but they better be worth it, because every time you send a team, your hq's defense will be permanently lowered, and it triggers an indoor mission having to hunt and kill the stragglers who manage to make it in.
the swarm will lower your defense rating over time anyhow, and when it drops, several millions of zombies swarm your hq.
it's up to you whether to give up, fight them 'till your last breath, or whether you were enough of an ass to go for the city's nuclear plant, blowing everything and every one up, or try to breach the quarantine set up by corps and government (no, you won't be able to, but that swarm on your heels sure will).
the game wouldn't have a win scenario, but every game over would also feature slides that say something about events unfolding after your passing, the fates of other characters, and a score based on how long you lasted.
fun gameplay elements would include stories that wrap around in circles, like people you lost in missions making their comeback as zombies, or finding out the consequences of your action... maybe that cop you ratted on to the internal affairs actually was innocent, but loss of job and purpose made him into a crazed child-abusing freak, whose home you now have to raid for stuff..
maybe the rookie you had to leave behind because he didn't run fast enough actually managed to barricade himself in a room, and you later find his remains and his journal all over the walls, how he held out, hoping for a rescue because you said you'd come back for him, but never did.
morale would not work like a score, but more like hitboxes, and would be entirely invisible to the player.
everything would have durability and require valuable resources to repair.
i can't imagine anyone ever doing it, but at least the zrpg is coming pretty close to some of its concepts.