Actually on a related note:

Red Faction 2

-make it more like Red Faction 1. :D

well not everybody would agree.

And our differences is what makes this world a beautiful place. :D

FO3, NV and 4

-Add more isometric combat options. Like the new XCOM, even! that was a pretty cool game.
I loved NV, though! I have over 200 hours on it, according to Steam :P

Wizardry 8:

Adjust the game's difficulty so that Arnika Road isn't as difficult.

Reduce the magic resistances of higher level monsters.

Place a few useful low level gadgets earlier in the game.

Make Ferro neutral for combat purposes.

Change the way enemy level scaling works: Instead of being based off your party level, have it be based off of game progress (for example, the number of artifacts you have obtained). Also, overworld enemies should be easier, and dungeon enemies (except in the monastery) should be harder.

Include an alternate way to increase stats.

Hide the Sausage:
- add more Daisy Fuentes

But seriously...

I-War 2:
- add the stuff that got left out due to time and budget constraints.

So many new releases these days:
- add the Day One DLC into the main game instead of selling it / them as an add-on.

Here's another one:

Baldur's Gate:

Make the game turn-based instead of real-time.
Make effects like entangle wear off automatically at the end of battle.
Tone down a certain enemy who can be encountered early game who uses Improved invisibility.
Drastically increase the experience from early game enemies.
Make Sleep effects not so powerful against weak enemies.
Give all ranged weapons unlimited basic ammo. (In other words, ammo management should only be needed when shooting things like Arrows of Detonation.)
Allow the combat log to be viewed after game over.
Get rid of "main character death = game over". Instead, when a battle ends, the main character is revived with one hit point. (Entire party dead would be game over.)
Get rid of dungeon traps and the corresponding thief skills.

Every RPG with no option for turn-based combat:

- Add option for turn-based combat.

Take an open world game like "The Vanishing of Ethan Carter", then add in the movie adaptation of Stephen King's short story "The Langoliers".

You land there on a planet and while there are these giant Pac-Man things eating up the ground as you're running away and pooping out space, you get a sudden time shift and you're running from the same room to the room you were just in before.

Then you finally shift into real time and get hit by the train which was behind you when you entered the tunnel at the beginning of the game.

Most 70's-90's games.

Make them playable that doesn't feel insanely awkward or unintuative.

(Or is that too broad of a scope?)

edit: Ahh yes, also most games: Give them manuals...

The Witcher 2:
Make it more like The Witcher.

The Witcher:
Include more references to Yennefer/Ciri (seriously, I played this before I read the books, and had NO IDEA Ciri and Yen were so central in his life AT ALL. I understand amnesia, but they should have been present.)

I could argue that any game that doesn't have turn-based combat isn't an RPG in the first place, so your improvement would apply to zero games.


Here's another one:

Every game that only lets you play male characters:
- Add the option to play a female character.

Resident Evil 5

-Remove Sheva!

There. Much better. 500% better in fact

Okay heres a few more changes.

-Remove QTE sequences
-Port the RE4 inventory system
-Make Umbrella the bad guys again.
-Chris can no longer punch bolders
-Final boss fight is not in a fucking volcano.

There I fixed it.

I'll just go by genre.

Action
- Stop with the death/kill animations. Having to stop mid-move and watch my character do some 8 second kill animation on an enemy is pandering to 12 year olds. It breaks the reflex skill, and is very annoying... especially after you've seen the same 5 animations 2000000000000 times in a row. Also, reloading 20 rounds into a shotgun should take longer than 1.5 seconds. Give gun play real world physics. It's honest, it's authentic, and it could bring back some actual difficulty to modern twitch shooters. At least make it an option for players who want a real world shooting challenge in a game that is supposing real world dynamics.

RPG
- Random encounters, side missions, and loot collection should be implemented in combination with the world they inhabit so that they make sense. Just plopping down a repetitive series of enemy fights or loot drops doesn't just not make a good RPG, it's not good game design. Crafting items, quests, or encounters in the world should be done with a WHY motivation rather than a HOW motivation.

And any 3D game
- If you can't enter a building, don't put it in the game. Too many RPGs and FPSs put in towns and buildings for artistic merit that are really just resource hogging window dressing. If I'm playing a game running through a city with 100 buildings, but I can only enter 3 of them, that sucks. It breaks immersion and crashes right through the 4th wall of game design. If the player can't enter it, use it, or in some way interact with it, why put it in the game? That window dressing trick may have worked on gamers 20 years ago... not so much now. If buildings have to have interior cell loads then fine, but at least give the player that option. It's a constant gripe of modern gamers, and it's one I agree with.