Two things.
Game wish one. The ultimate MMO.
The game world would be user Fueled. Players join together to create towns and cities and eventually countries. People can join these player cities and get benefits unique to each town as Chosen by the towns current leaders. Fighting over resources and land in the game world against other players. Totally customizable characters. Earning experience grants you he ability to create and modify your own moves. Instead of getting "Fire rank 1" you train in fire magic and modify it the way you wish. Spend experience increasing the damage, making it so it fires multiple projectiles, reduce charge times, create AoE effects as well as mix schools of magic together keeping players on there toes.
You see a Mage from another town, you draw your sword and he throws a fireball at you, but whats this? The fireball has poisoned and slowed you. So you leap at him and to his surprise when you land instead of trying to strike him you land behind him and crack him in the back of the skull stunning him for several seconds.
No two spells would be alike, no two swordsman have the same moves. One is lightning fast master of blades while the other is a powerful spell knight calling down lightning while cleaving your head off with an axe.
In other words no classes outside of what you create. Think you have the best abilities? Start a guild and train other players for cash.
Did i mention real time combat? I would prefer it to be a console game so that a controller could be the standard. Headsets for party Chat. Magic spells aim like an FPS in over the shoulder view and instead of a cast time you can charge the spell to increase its damage and expending extra Mana. The longer you cast the more deadly the effects but the more mana used. Melee abilities would function like a brawler and of course ranged abilities would function like an FPS as well.
Incredibly deep crafting systems. Instead of "You need two silk spools and a spider egg sack" you can create items out of anything that meets the basic description, with better materials the better the equipment. As well as the ability to dismantle any old gear for parts. An experimentation feature that allows you to manipulate stats on a to be crafted object, or take a chance and flat out boost some stats but with a chance to accidentally destroy the materials used.
There is a lot more but its about ten pages of specifics. Honestly.
Game Wish two.
A zombie game that's NOT about busting zombies but rather survival and preservation. Your goal is to survive not bust as many undead as you can. A rich stat system that you never see. Literally. You are never told your strength or stamina you can only assume from results. No need for stat grinding either. Everything can be done from the get go. You can climb that fence but a low strength and agility score means you going to have a hell of a time pulling yourself over. If a door can be kicked in you can do it even with 1 strength, just don't expect the process to be quick, or quiet, or not totally ruin any chance of using that door to re barricade the room. That way players will grow naturally through actions and never feel the need to jump over a fence for three hours.
Everything is a weapon AND a tool. Things like screwdrivers can be used to take doors off hinges, crowbars and quickly open locked doors and containers as well as quickly open a manhole cover. A fire axe can be used to demolish wooden structures in your path or carve through a gyp rock wall.
A massive city to explore. Hundreds of other survivors. Each with Stories, friends, family, and clues to how this all happened. How you treat them is up to you. Helping someone escape a zombie attack could yield some resources, maybe a new skill. Or you could get jack shit and have just wasted some of your own supplies. Or worse its an ambush by raiders and you get all your shit stolen. Not morality but more your actions determine how certain people think of you. Kill someone you can take all of there stuff. If someone sees you though they and anyone who talks to them may now be hostile, or you could lose the chance to learn a new skill from that person. Then again you could get much needed supplies in a time where your running low.
Life, Stamina, and Panic. Your life bar self explanatory. Your stamina does a great many things. Whatever turned almost everyone into zombies has turned you into something so much more. Your body can regenerate non fatal wounds as long as your Head and heart remain in tact. Every bit of damage knock a bit off your life bar but is then slowly regenerated by your stamina. How fast relies on two things. How well fed you are, and how much of a panic your in.
Panic can be increased by two things, receiving damage or facing massive odds, like a wall of zombies. The more of a panic you are in the more damage you deal hand to hand or with Melee abilities, the harder it is to aim with ranged weapons, you use less stamina to heal but you heal at a slower rate. You also can run and move quicker with less stamina as well your stamina bar itself recharges quickly. While calm you heal quickly and can shoot with better accuracy.
Once again... there is a lot more to it, only this proposal is only 6 pages long. Thanks for reading.