Actually NQ Mod with its Maps maybe
Here are many things that is wrong with Civ 5. I love the game but there are so many things that are just busted lmfao.
And I am about to cover most of them in 1 post.
The Civs.
Poland - Best Civ in the game and no one is going to question is.
Spain - Buy settler turn 3.
Venice - Worst Civ in the game.
Babylonian - Scales amazing througout all points of the game. Early Bowmen + Their UB is extremely good. By the time they get Crossbowmen, you're still in early game. Not to mention they have this UA for like, no reason??
Earn Great Scientists 50% faster
This makes them really good lategame I'll explain in a bit because Great People are busted in all of themselves.
Arabia - CAMMELS. Best unit in the game. Being able to move at the speed of a knight + shoot plus having extremely solid stats is stupid. Also Petra.
Ethiopia - Best relgious civ by far. And for good reason, their monement replacement produces FAITH. This changes my personal build order from Sscout --> Scout --> Shrine to Scout --> Monument Replacement (I actually haven't played in awhile so I can't remember if that was the optimal strat or if it was monument first then scout). Either way, they will ALWAYS be the first to get religion.
England - Longbowmen having the range of 3 is amazing. Also Frigates combat stat is 25. Their Frigate replacement is 30??????? Combine that with their UA and you have the best navy civ in the game.
The Huns - Really good military civ especially early. In fact, if your capital isn't on a hill, and they have a battering ram and attack you. If you don't have an immediate response to the battering ram you can say goodbye to your capital. Also their Charriot Archer replacement doesn't require horses and Charriot Archers were already a good early game unit.
Ican - Hills were already good, so lets make them their strat bias and give them not maitenence cost. One thing I like to do is just build roads on all of my hills. They cost no maitenece and you get free mobility so why the fuck not. Also Terraces can yield lots of food and can become extremely strong. Not to mention if you have mountain access already you're giving yourself access to Machu Picchu and Observatories and those are just good things to have as well.
Iroquois - Why do they have a terrible replacement for the workshop???? Ok, the real reason why this civ is unplayable is because their UA doesn't actually work. Like, its a fucking joke imo.
Korea - Turtle Ships are a good meme, but not why they're broken. Their UA is. Because 2+ science for each specialist adds up. Also the tech boost is just lol.
Mayan - Great UA. Amazing Shrine replacement.
I think that wraps up most of the civs.
The wonders I think for me the most really busted wonders I would have to say would be Petra because plains are already some of the best tiles in the game, and you're turning dessert tiles into plains tiles (1 hammer 1 food). If I have Desert Hills near Fresh Water + Petra, I build farms on those, because a 3+ food 2+ hammer tile is really strong. It also makes spawning in Dessert, and Dessert Bias Civs (Egypt, Arabia, and I think Zulu?) really strong.
And Alhambra because Blitz Xcoms. Alhambra is a really good wonder because of the free promotion. This always you to (and with all unit upgrade buildings) get Blitz Xcoms. Those are really strong because you can paradrop and attack on the same turn. This esssentially allows you to Stealth Bomb and/or Nuke a capital to the point where you can take it, paradrop, and take the capital. All on the same turn.
Social policies honestly liberty would be a stronger if the maps suited a wide playstyle and if building national wonders didn't cost so much because you wanted to go wide (also pro tip. If you ever DO want to go wide, settle on unique luxuries, you'll get the happiness from them right away if you have researched the tile improvement for them). Like, you lock yourself out of (most notably) Oxford (btw another pro tip, ALWAYS save this for the late game) and National College.
Otherwise we go 4 City Tall Tradition.
OKAY
NOW FOR MY FAVORITE GAMEPLAY MECHANIC.
Did you know that Great People like the Scientists and Writers will yeild the amount of Science (for Writers Culture) you produce within the last 8 turns over having a set amount?
So what you do Mid game is you start saving your Scientists,
Completely ignore the bottom half of the tech tree and beeline Research Labs (plus the military techs down there aren't as important as getting the million over things that are important, so beelining Research Labs is better in general)
You can either keep holding onto Oxford or Oxford into Research Labs.
Build Research Labs in all of your major cities.
Wait 8 turns.
And start popping off 1 great scientist per turn.
Beeline to Hubble
at this point you should have a Great Engineer, Engineer Hubble
And then what you do is up to you.
Do you want Stealth Bombers?
What about Nukes?
Or maybe Xcoms?
You can now beeline them and start dominating and earning your military victory.