Dump the Zombie vs. Player system (don't worry there's still going to be Zombies)>The player starts up at first normally (no character skill menus or arsenal variation menus) being born, and after all the creative aspects involving the parents the player decides the character's look (Fallout 3)
Create a world involving supernatural theme horrors, AKA Vampires, Werewolves, Androids, Goblins, etc.
Introduce the game as a blend of modernistic and supernatural elements
>The game should start out realllly modern, and I mean computers, cars, cell phones, and a lot of gray, there should also be a lot of citizens walking around
>However, with all the goodness that exists there should also be a really creepy secret in the midst of the civilization
>The player goes around with his grown up child character and soon discovers that the city is enclosed by a dark rural landscape
>Upon further discovery of the city's dark secrets, a few of the gameplay elements are introduced
>You come across agents under the control of the city leaders and you must escape them (the Health, arsenal, etc. pops up)
>The agents question the character's dangerous curiosity and attempt to capture him
>The player has to guide the character through a chase into an abandoned house
>The agents that close the door and light the house on fire
>The player's goal at the time should be to escape but it should be obvious that there's no way to escape until you fall through a hollow floor panel
>After this you blank out like what would happen in all elite class games and you wake up in a sewer carried by a flow of water to somewhere far away from the city
Well this is when the supernatural elements should start to form. The character is wearing modern clothes and all that and he walks into a world that is totally medieval. No guns, cars, or skyscrapers. Let's skip all the confusion and surprise and get to the goal: The character needs to escape this world consistent of legendary horrors (vampires, werewolves, supernatural wars, androids). The villagers that are there during the day should be murdered, the character discovers that there are wars going on and runs away even deeper into the chaotic world. After a while of traveling and talking to strangers the character should find a town controlled by a demented priest, and eventually start finding information of this world (the villagers have no idea of the 'Paradise City' that exists). The character eventually finds his way to the borders of Paradise City but only after the character has undergone a few transformations (depends on if the character wants to be a werewolf, a warrior, vampire) with his clothes, arsenal, and mindset.
The player has to sneak the character into the city because you discover hundreds of agents walking around with machine guns (don't tell me how the character does it) and once in there a new discovery is made: the character's parents are dead and an army is being prepared. You're eventually discovered and the agents bring the character to the city leaders where they question what he found and try to calm the situation down. However an alarm rings and an attack occurs from the outside. Werewolves, zombies, vampires, androids (Frankenstein's monsters), villagers with medieval weapons, and a lot of other lethal stuff come pouring into the city and you're the only one strong enough to defend it (lol). After the city goes to ruins you're transported to the other server where the other players who finished the story mode already are helping to defend the city and rebuild it but also trying to spread the civilization all the way to the ends of the world.
Keep the game name, it's fitting
So yup, that's my idea. Some concepts are taken from other games/movies/books but it still sounds pretty good to me. Maybe that Monster Kingdom game you made could be merged with Paradise city to make this game.
However, this would be an AMAZING game, although it would be pretty hard to make. Though Falacy probably can do it, it would take AGES. Falacy ain't god, he's more of a demigod or a Hercules.
Story: It sounds good, but I think throwing in a bit more of a bang to get straight to the crazy shit would be a good idea. I think something neat to add would be some kind of goddess, and you would see statues of her and paintings and books of her all around the city. Than there would be a command you'd always have that would allow you to view the mythology about how the all the stories about monsters were once real, but then the goddess appeared and banished all the evil away. Then one day you look around and you find no one, and the main statue of the goddess is gone and there is a strange portal there instead. Maybe out of the portal comes a monster that knocks you out, but you get rescued and taken into the world full of monsters. I like that more because your tutorial seems like it stretches on too long. Here, you choose to fight in different timelines, you could choose Medieval, Present, or Future, each with their own enemies and weaponry. Throughout all 3 there would be one organization that's the exact same in each time zone, and that would be the central hub area/HQ that's main purpose is to find the lost goddess and until they do, protect the last of human civilization across 3 timelines. You could choose to begin your adventure in the medieval world, the present, or the future.
Game mechanics: I think a quest system here would be GREAT, along with a minimap that has quest markers perhaps? First it would take you through the beginning tutorial area more easily just in case you forget what to do. And when you get into the full world, there'd be lots of quests like "save my son", or "find my husband", or "Please get my prized possession from this infested place". Maybe you could do sidequests like that once or twice a day? And doing that would increase some kind of Pure vs Infected percentage rate, which would then be restarted if it reaches 100% pure. The Pure percentage can also be increased by killing monsters, but is increased more with sidequests. And the more pure the world is, the fewer monsters there are but the stronger they become. You would always be able to see the Pure vs Infested percentage in a tab, and it would have the percentage of each timeline. And a constant bounty list in the HQ centered around defeating the most famous monsters throughout history who could have their own dungeons. Monsters like Frankenstein and Dracula. Those dungeons would also be centered in time.
Overall, I like this idea though I don't think it should be thought of as Paradise City, since the universe and concept is completely different. Infact, it'd be better if this was moved to the general section as a new game idea IMO.
Most of this post is focused on the post-tutorial which you were a bit vague about. I did change the ideas quite a bit but I used your idea of monsters unleashed in the world, and people focused on rebuilding the city and protecting it.
EDIT: Got a few more ideas while thinking about this.
Items/Weapons/Armor: There could be a Melee/Ranged/Magic-healing classes that are decided purely on your weaponry and skill that would go up when using each one. Skyrim anyone?
Present: Melee class would use clubs, swords, and machetes. Ranged would use guns focused on medium/short-range, shotguns, as well as snipers. Armor would be a choice of heavily padded armor for more defense but less speed and evasion or light armor which would make you faster and give you more evasion but less defense.
Medieval: Melee class would use long swords and shields, as well as options like spear for a 2-block attack. I could use some more options if anyone's willing to give some. Ranged would use bow & arrows as well as boomerangs. Armor would be similar options to present, but you'd have either metal armor or chainmail.
Future: Melee could use energy swords or lightsabers. Ranged would be able to use plasma guns or futuristic guns like that. Here, you could choose armors with special abilities such as increased speed boosts or the ability to teleport a distance a few times, but with a cooldown.
Magic: I had completely different plans for magic which is why I didn't include them in the Medieval/Present/Future. Magic could be seperated into classes. One based on Buffs/Healing, One based on elemental attacks, and one based on taming enemies and summoning them? You would have a spell to attempt and capture them, then you can place them into a special gem. Different gems would be needed to capture different types of monsters (undead, creatures, types like that). They would be expendable though, and if they die in the HQ you can revive them, however this would be costly and only useful on stronger monsters.
Items would be fairly generic other than the gems I mentioned. Healing items that heal instantly and over time, buffs, grenades, most anything like that. Along with quest items.
This is a really interesting idea to me, and if anyone has anything to contribute I'd like it if you said it.
Items would be fairly generic, things like heals, grenades, heals over time items, maybe special charms to increase certain stats. There should be quest items as well.