It's a start, but I recommend building on it a lot more. At the moment, there just doesn't really seem to be anything unique about the scenario that really distinguishes it from being typical zombie apocalypse fare. I've seen RPs like this before and no one lets their character come even close to becoming infected. Everyone will pretty much have guns that never run out of ammo, escape vehicles in easily found spots, and plenty of zombies that might as well have targets painted on their faces. By the time most people have finished off their fifty-third zombie with a buckshot blast to the face, they'll probably be looking for some new RP to get into.
Also, Sector 9 needs better and more believable motives for what they're doing. If they destroy the world, well, they're pretty much dead too. They'll have no one left to farm food, no economy left to fund their operations, and so on. Instead, they should really be trying to find a way to leverage their weapon for control and compliance from other world governments. Even the most deranged and evil of terrorist organizations still have lofty motives. And yes, even the Nazi regime envisioned a better world after what they hoped would be a successful campaign, regardless of how downright wicked the means were.
As such, Sector 9 needs a similar approach and mindset. If you want this faction to continue spreading the zombie bio-weapon, then it needs to be for a reason that they'll feel will better their situation than what it currently is now. Maybe the bio-weapon targets certain demographics/locations that Sector 9 feels society would be better off without, or so on. Or, Sector 9 already has the cure to the zombie virus, but only those who they deem worthy to survive will be allowed to have it. This would work because if Sector 9 just wanted to destroy the world, they don't need zombies. Nukes would do the job even better.
Here are a few things I'd recommend for an effective zombie RP:
- You being the narrator. You, Tasslehoff, determine what kinds of zombies and creatures are going after the characters and who/how they attack. If you leave that to the players to decide, they'll never face anything even remotely dangerous and will likely never take so much as a scratch.
- Player character inventories and health statuses. This is so people don't pull guns/tools/first aid out of nowhere and have to account for how much ammo/supplies they have left (ignore reloading aspects, as that's a pain to account for). Limited inventory space will also force players to decide what is worth keeping and what needs to be discarded.
- Scavenging for supplies. Allow characters to search areas and discover supplies/weapons/ammo. Players may perform search posts, but you, Tasslehoff, determine what exactly they find. Since you're controlling the antagonists anyway, they have everything they need. It's the players that have to struggle to find what they need to survive.
- Hunger levels. Finding food and having a hunger status will put a little more pressure on people and add onto the challenge.
In essence, players would declare each of their role play posts to be one of four types:
Traveling - Moving from place to place. If they're busy driving, running, or whatever, they're not doing very much else.
Searching - Looking for supplies. If a person writes a very nicely detailed search post and searches wisely, you, Tasslehoff, reward them. Also, make their searched items relevant to where they're searching. Searching a police station will probably yield weapons and ammo, a supermarket will result in food supplies, a hardware store with some melee weapons, and so on.
Communication/Exchange - Conversing with another character and/or trading supplies (if the conversation lasts longer than 3-4 minutes, realistically). Cell phones should be dead, so the person can't exactly talk and search/drive/fight at the same time. The only time I wouldn't count a post being spent entirely on communication is if they're traveling and both conversing characters are in the same vehicle or walking together.
Fighting - Any post where they attack or fend off any kind of zombie or creature. Sure, a character could attempt to fight from a moving vehicle, but they won't be making much progress in terms of traveling and distance.
You don't need to implement HP values or that kind of thing (I've tried this before, it very quickly becomes a complex headache with chance to hit, armor, attack rolls, weapon damage, and that kind of junk). Keep things simple, but add to the challenge and leave some things within the control of the players, but leave a lot of other things out of their control.
I'm not saying you HAVE to do something like this, but I'd consider the idea of making survival a struggle for the characters, and throw surprises in their faces. A risk and reward system will very likely make the role play more interesting and will make people want to keep on exploring further rather than get tired after killing two dozen zombies that never had the chance in the first place.