Yes, I don't know the limit flash can go up to,if there is a limit.Maybe like an overworld game or something similar to ThingThings zombie survival mode.
Even if it were possible to make a game, 3-D is out of the question. Most of the flash games we have here aren't, and they were fine anyways. Even if you were to make the biggest, baddest flash game here, it would take too long to load, getting poor marks for that. You gotta think more creativity with a decent balance of quality.
anybody that whinges about long load times and rates a game poorly because of it should be shunned. sh-sh-sh-shunn-n-n-n-n (the non-believer)! well, as far as a L4D flash game... I just played L4D at my friends house today, and it was amazing, but on easy mode dual pistols can easily wipe out hordes... back on topic!!! that dead frontier mmo is similar, but I tried it and it's just..... to realistic in the amunition department. You spend the whole time using your knife to kill zombies while you loot instead of blasting them away, and the stupid aggro system and the crappy health meter (a percentage was too much for you to handle???) made me stop playing. On another note, if you want you're horror/err... not much shooting, so I'll say fighter fix, go there.
so, that's an alternative if you REALLY want to play a zombie game with some friends, but as for a L4D flash game, wouldn't that break copyright rules? and, 3d is way out of the question, so the game would either be top-down or sidescroller (just doesn't work with a shooting game... I use Thing-Thing's brokeness as an example) and just not the same. So, nobody (as far as I know) is working on a game like that, except for the dead frontier game, and that one was too hard to enjoy...