imalittlcreeper i might consider making your game i might im noy sure but yea i might ok

A game of complete life, where you could do anything. You could buy houses get jobs and do cool stuff. It would be kind of like MySims, but more detailed.

You are the doctor. You can create your own doctor and your own TARDIS to fly around the universe. There is a London-esque city which is like a "base" sort of thing where you find partners and such to go through time and space, but different real-time events can occur there and you would have to sort them out and save the city. You could explore a heap of different events from the Doctor Who universe and some others, also depending on what happens and how you do things the story can change.

Multiplayer stealth/espionage action platformer.

Play as spy, hack consoles, steal intelligence, kill other spies. Y'know, that sorta thing.

i would make a game of what me and my mates played as kids you play as a boy and you are murdered but you come back to life as a skeleton and you use a portal to get into a undead world and the humans follow you and want to take over and you save the undead world and your are named skull-kid but there is a curse and then that gets to you and creates a evil double of you that will destroy the world at the end but you get to kill him and you can get guns and dragons and loads of cool things

Neptonic
Not using a ( per object ) hit-scan system?

No, i used That method in my first FPS Minecraft Clone and it led to imperfect results ( the scan can miss thin parts of block corners and it turned out to be a non-trivial problem which led me to write a 3-D scissoring algorithm which moves one hyper-face per step )

RevolutionalRedStone
First person shooter... especially the perfect bullet collisions involves writing a spatially inclusive real-time ray-tracer )

Not using a hit-scan system? The hard part is the gravity systems such as crossbow bolts and thrown explosives.

That game i would make would be...
Something ALMOST relevant to minecraft.
But would have some physics.
Like gold would fall down, trees would timber, many things.
But most of all, i would make a game that would involve lots of shooting.
And make it based of mega man! I will call it maverick hunter!
Huh? What's that?
Capcom cancelled a game that was named that?
God dangit.
Freaking capcom >:(

Well I'm in that position every-day : )

As a long time games programmer I've tried my hand at every genre.

My favorites are:
Real time strategy : very interesting to write : difficult parts include writting the poly-unit path finder and the poly-unit A.I.

First person shooter : very easy to write, especially the multiplayer aspect : difficulty's include writing a perceptually-perfect method of interaction ( perfect player collisions usually involves programming a hierarchical bone structure, perfect bullet collisions involves writing a spatially inclusive real-time ray-tracer )

My other favorites include:
2-D platformers ( quick and dirty to program, lots of time taken and fun had to play )
Space games ( lots of room to play in terms of levels of detail; opportunity for excellent graphics and art )
2-D topdown MMO RPG ( a real thrill but no challenge to code, and alot of love and feedback from players, and ofcoarse alot of fun to play ! )

Thanks for an excellent question.
Also you would not have heard of any of the languages i use ( Archaic, DO, Seventeen ) because i invented there syntax and wrote there compilers.
( ill give you a look at them if you'd like tho )

Hmm...
I would make this game. It's a bit like battlefield ( not story mode ). You have Laser Grapling Hooks and the map is floating islands, many of them. You have different guns and you just battle each other while flying around with your Grapling hook.

Or:

Bioshock Infinite Online. It's just a Bioshock battle mode with all those fancy plasmids and stuff. I think it would be awesome.

Or:

The Legend of Zelda: Twilight Princess Online. I think you know what I mean.

All Great ideas i might choose to make one of these games for 1 person! But ALL VERY GREAT ideas

I would make an RPG that's kinda like Skyrim but in the Harry Potter universe which takes place before Voldemort. You could go to Hogwarts or the two other schools and go to classes skip classes then after seven or eight years(in game time not real life time) the player could choose what he wanted to be based on his marks in his classes. Spells would be skills you could learn upon level up and you could get experience for using certain kinds of spells. Like fast travel would be Apparation,(In the movies they were just sucked inwards and were teleported somewhere else) and Apparation was a skill that had to be learned.The other way to get around would be by broomstick. Also it could take place in the muggle towns as well and if you used spells in muggle towns/cities and being noticed you would get a bounty on your head. However there are still dark wizards so, if you want you could join the Aurors(good guys) or the dark wizards(bad guys). That would be the game that I would make. There would be one problem though. There would have to be so many places to go that there would not be much space left for much else.

Legend of Zelda w/ free roam of Minecraft.

I would make a minecraft as realistic as Slender the Arrival and also id insert gamemode Slender or Herobrine where it takes the minecraft edition of Slender: The Eight Pages.

I would make this game-
You can literally live anywhere you want. You start off as a baby, no saving, no choosing what gender or race, once you get badly hurt the screen gets dark and you could end up in the hospital in two ways, injured and the same player, or as a baby and a new game starts. EVERY PLACE IS ENTERABLE! No mesh stores. You can buy anything, get married and things I won't go into detail if you knows what I means
You can also have pets, and to satisfy everyone, rob, have guns, etc. but you live a bad life because you have to live undercover. You can escape jail but you have to click A 200 times to use a spoon on the wall. You can also drive, eat, sleep, poop (and if you don't then you get dirty which means you have to wash your clothes to be socially accepted). And you go to school in the beginning which you can drop out of
You practically live life but you can mess it up too.

I'd make a role play game of Avatar The Last Airbender. Where you can choose to become an element. And someone is randomly the avatar. Someone could be a Zoku person. Katara person, Pakku, or the other people! Or you can just be random cabbage people. >:P

Mine would be Half-Life 2: Opposing Force 2 on the 2007 Source engine (The one from Episode 2). It would follow Adrian Shepherd through the now Combine ruled world at the same time as Gordan Freeman in Half-Life 2, taking out the Combine's Synth factory out in the Wasteland.

(GABE IF YOUR READING THIS MAKE THIS GAME SO I DON'T HAVE TO MYSELF)