What would you do if you controlled a franchise you liked?

[Trippy Turtle]

I'd ruin it no questions asked. I'm just shitty at stuff like that.
Other than that though, I'd take Halo back to its Halo 2-3 style multiplayer and make another game probably. With a better firefight that has weapons around the map you have to buy and basically clone cod's zombies
I'd also try and make the campaign have Halo Reach's difficulty, Halo 1's level design and 2s story. But not rushed like 2 was. And of course Halo 3's custom games and forge.
Also I'd like to include more from ODST but despite its story and campaign being amazing it just doesn't mesh well with the rest I'd imagine. Perhaps its noir style?
A man can dream.

 

[Johnny Impact]

I haven't liked Sonic since Heroes on the GameCube, but I've wanted the Sonic game that should have been made for years and years. I'd get the whole development team together (or hire someone else), slap down a few dozen copies of Burnout: Paradise, and say, "Okay, you fuckers. This game is your classroom. I don't want a single line of code written until you've all earned platinum trophies." I think the solution to the I'm-losing-control-dodgy-camera-help-I'm-stuck-in-a-giant-pinball-machine feeling is just to discard the crazy bouncing action in favor of an open world racing game. Essentially I want a re-skin of Paradise: earn better shoes instead of better cars, rings as collectibles like the smashable gates, other speedsters racing around waiting to be challenged, Marked Man-style events where Sonic has to survive high-speed confrontations with dozens of Robotnik's minions, best times uploaded to taunt your friends, and so forth. Two things above all: 1) the game has to feel FAST, like trying to control someone with the Flash's speed and Spider-Man's agility; 2) not released until it's good and ready.

I'd get Half-Life 3 released, though again, not til it's ready.

Three words: System Shock 3. And no goddamn dumbing it down or making it too easy this time *cough*BioShock*cough*. I want to feel like ammo and health are finite resources to be shepherded, not trip over them everywhere I go. I want to agonize over which skill to raise. I want mods on my mods on my stat points on my inventory screen! And while we're at it, HD rerelease of Shock 2.

 

[Rahkshi500]

For me, it would be Nicktoons Unite.

I would probably reboot the series with a larger cast that have more varied screen time instead of having Spongebob hog most of it. Probably would be a beat-em up game, or maybe an SRPG, probably in a more "combined" that borrows elements from each series present in the game. And probably would feature an original protagonist as the player-insert character to go on adventures with their favorite Nickelodeon characters.

 

[Brian Tams]

Halo.
First order of business, fire everyone at 343 and launch all their work into the sun. They suck, end of discussion.
Get rid of sprint and customizable classes because fuck that shit, we ain't CoD. Turn the player movement up to DOOM II levels. Bring back non-regenerable health and health packs, because god forbid we actually have to use some logical thought when it comes to map balance.
Bring back the extensive map editor from Halo: Reach.
Bring back firefight, except give the players even MORE control. Player control is good, guys. Lots of customizable options is how you extend a game's life without cramming DLC down our throats.
Get rid of worthless execution animations. Seriously, guys, just a simple whack to the back of the head still instantly kills them, no reason for bad players to go into the lengthy killing animations for a simple assassination (and get picked off by actual good players in the middle of it).
Halo 2 ranking system is back. Absolutely zero reason to have gotten rid of it. The only difference is that the player will have an option to reset their rank so that we can avoid delevelers this time around.
Unlocking new armor bits is fine, but its all purely cosmetic.
Speaking of armor and cosmetic things, our entire DLC ecosystem will be through new cosmetic items, such as armor, new voices, visor colors, etc. etc.
Duel Wielding weapons will once again be a thing. No reason for it to stop being a thing.
And that's just the multiplayer

Campaign
Halo 4 is officially non-canon. The Elites are once again our friends as they were intended to be after the events of Halo 3.
Ignore the Halo EU. I'm not going to expect my audience to have "done their homework" in order to understand what the fuckety fuck is happening with the story. We will employ professional writers who won't use the works of others as a storytelling crutch.
Master Chief & Cortana will not be recovered. They will stay on that half a ship for the rest of eternity.
Instead the new game will focus on the Arbiter, because he remains the most interesting part of Halo 2. But because the average Halo fan failed to appreciate the beauty of showing multiple sides of the same conflict and bitched because their precious bromance time as the Master Chief was interrupted, the Arbiter was relegated to a supporting role in Halo 3 and forgotten about in Halo 4. Fuck those guys. *hugs Arbiter* Its not YOUR fault nobody understands you!
The Prometheans from Halo 4 are fine. The Prometheans worked as a concept, they just failed at the execution.
Speaking of which
The Promethean AI will be programmed by the guys who did the AI for Halo: Reach. Seriously, that was some of the smartest Halo AI yet, and for whatever fucking reason 343 abandoned it for their shitty bullet sponge AI for Halo 4. Seriously, fuck 343.

And finally, two final points.

1. We will bring back Marty O'Donnell in order to restore balance to the Halo Musicverse

and

2. We will also be releasing on the PC. With mod support.

EDIT: Almost forgot

And, when we have sold tens of millions of copies and have been hailed as game of the year 3420 different times, we'll release a modest ten map multiplayer map pack free of charge as a thank you to our fans. Remember when fan appreciation was a thing?

 

[Duster]

I would take doom 4 and help them with the development. I'd make sure they have their priorities straight.

1. Fast, challenging and engaging gameplay
2. More forms of replay value, track times, stats, have a super hard mode
3. Sense of awe and atmosphere
4. coop support
5. Narrative tacked on would be a cute sci story with some allegories to Christian literature/publications during Crusades, Enlightenment, Inquisition and Renaissance with room for fan theories and continuity.

I actually skimmed through a lot of this thread, interesting perspectives.