Remove 1 letter from a game title and provide a new synopsis.

Part Hard - the other part flops around like a limp noodle, kind of like the average white guy dancing
Rackmania - I dunno but it somehow involves nice racks

RMA 3 - This is the third time you've had to return your faulty game disc to Bohemia Interactive. But you forgot to write the RMA number on the returned product's packaging. You're so pissed that you declare war on them.

Left 4 Dad - A game where you're left alone with your dad....
Pankiller - A game where you kill mutated frying pans :3
Two words

Ears of War
Layers of Ear
Lime Rancher

Zombie Diver HD - diving simulator of undeads
Dinosaur Hut - build a house for the T-Rex
Two Words: Epic Edition - like two digits, but two words
Meadowlad - guess it's a game about leprechaun
Trapped Dad - help the dad to get from the maze
The Sip - drunk party simulator
gg returns home - xD
1bit Trader - sell or... not sell
Tree digits - puzzle game for kids
Eat Tower: Kuon - should eat really a lot to win the game
Diekick - kick or die!
Gemraft - magical raft adventures
The Blue Flaming
Gun Meal

Tomb aider: you play as Ara Coft, a henchman, who's job it is to protect a tomb used as storage for cocain. You kill everyone who gets near. Even pesky tomb raiders.

The Lord of the RNGs - the game all about luck, no skill involved

allout - Survive in a post nuclear world.

Natural Election 2 - nonstop voting fun!
Guacamelee! Old Edition - all starts again when our hero meats his enemy at the same retirement home

Guild Was - The Guild that was
Perfect Word - An MMORPG where players fight for that Perfect Word
Endless Pace - A never ending Turnbase Speeding game
Duke Nuke - You play a Badass Nuke
Mineraft - You build rafts for nothing

Cunter Strike: Global Offensive
Town of Sale
BioSock
Dot 2
Ace it
FatOut
Oat Simulator
Excells
Nights and Merchants
Left 4 Dad

Lan Wake - An emotional story about a gamer waking up at a lan party and realizing he slept through most of the event.
Rack - A game about...well, I think you know what this is about.

METAL GEAR SOLD - economy is tough, your mission is to sell gear to keep motherbase afloat

(Rust) Rus - Soviet Russia invades all social media and neckbeards have to survive by collecting fedoras.

Removing a letter:

(BattleBlock Theater)BattleBock Theater- A game where it's an all out free for all battle against chickens set in front of thousands of people.
(Don't Starve)Don Starve- A game about a guy called Don, who is starving.
(The Escapists)The Escapiss- A game where you have to escape your "life" of the internet to take a piss.
(Evoland)Evolad- A game about the evolution of lads.
(Garry's Mod)Garry Mod- A game where you mod a cyborg called Gary.
(Goat Simulator)Oat Simulator- A game where you play as a bowl of oats.
(Hero Siege)Her Siege- A game about a female stealing things.
(Small World 2)Small Word 2- A game about making small words.
(Space Colony)Space Colon- A game about punctuation in space.

Changing a letter:
(The Binding of Isaac)The Minding of Isaac- A game where you look after a child name Isaac.
(Crypt of the NecroDancer (Sorry about this one))Crypt of the NegroDancer- A game about a dark-skinned person who loves to dance.
(Goat Simulator)Boat Simulator- A game where you play as a boat.
(Portal)Mortal- A game about life and death.
(The Stanley Parable)The Stanlee Parable- A game about Stan Lee's life.
(Starbound)Statbound- An RPG game about improving your stats (This is all of them though).
(Team Fortress 2)Beam Fortress 2- A game about protecting your fortress with lasers.

Adding a letter:
(Ace of Spades)Face of Spades- A card game where the only cards are spades, and the cards are played face up.
(The Binding of Isaac)The Blinding of Isaac- A game where you have to blind Isaac
(Garry's Mod)Garry's Mood- A game where you have to figure out what mood Garry is in.
(Goat Simulator)Gloat Simulator- A game where you have to tell everyone how good you are.
(Team Fortress 2)Steam Fortress 2- A game where you protect your fortress that creates steam.
(VVVVVV)VVVVVVV- Help Captain Viridian find his six lost crewmates!

Nobody mentioned these yet (maybe for a reason)
Zack zero (Ack0)
Zack zero
Triple town
WoRMs
Aero's quest
And Yetit moves
Braid
David
Crystals of Time

Orderlands 2 - a game where your objective is to order burgers from a local fast food chain
Metro 203 - a game about just a plain metro named "203"
Roboraft - a robotic raft ....
Everwinter - lol wut this is actually a different game ?

Last Days of Spring = Last Day of Spring.
A horror story about the final day of spring vacation before being forced back into slavery at school.

Sid Meier's Civilization = Sid Meier Civilization
A X4 Strategy game about colonizing the planet Sid Meier.

The Walking Dead = The Walking Dad
Its a Dad, that walks! The Horror!
Heck... if someone made a Shower with your dad game, then they'd probably do this too... Oh wait.

Darkstone = Arkstone
Story of the Arc that sank like a stone to preserve two of every species of fish/

Among The Slee...
Among The Sleep

View attached image.

Metal Ear Solid V: The Phantom Pain - You are a senior war vet having problems with his shiny metal hearing aid.
Metal Gear Solid V: The Phantom Pan - Tactical Espionage Cooking Operations with Prototype Phantom Cooking Paraphernalia
Dot 2 - Pay $2.99 for cosmetic dots.
Mad Ma - In this post apocalyptic austrailian wasteland, one woman will cross the plains of silence. its your mum.
Killer is Dad - In this world, Contract assassination is a stable career that brings home the bacon. The catch? the killer is dad.
Sniper Elite: Nazi Zombie Amy - Move over, zombie hitler, there is a new dictator in town. Her name is Amy.
Bound By Lame - You are a generic RPG hero who gets possessed by a demon with the powers of Lame.
Hoefront - America gets taken over by a nation of hoes and their hoe army.
Natural Election 2 - Space marines vs Aliens in an intellectual debate battle for the chance to be elected by the citizens of the planet they are currently in.
Death to Pies - WW2 era steath action pie simulator.
T.A.L.K.E.R. Shadow of Chernobyl - You awaken to the new world. Where the newest, most dangerous profession is now a talker. Someone who spends all day talking with people in nuclear chernobyl.

Tea Fortress 2 - group of British gentlemen protects their supply of tea
Cave Sory - game company known as Cave tries to regain the trust of gamers after focusing on mobile gaming
Gat Simulator - educational game about weaponry
Loo - adventure game centered around toilet humor
Underale - travel underground to taste the finest beers

The Secret Word - Manga dating simulator, where only one word turns a girl on...
Lan Wake - Game about a boy, who is organizing a lan party, but the modem doesn't want to cooperate
Injustice: God Among Us - A really religious game, where we can play as God
Lie is Strange -
NO A HERO - Villain simulator, where you have to kill a lot of heroes, while you fullfil your evil plan.
Ace the Sun -
Spec Ops: The Lie - The antagonist was your best friend all the time!
Evils Share - You can never escape from your past
Enemy Mid - Worst CS:GO ripoff, where the map is only a single corridor with no covers
Enemy Font - Comic Sans, Bank Gothic, Trajan and the other fonts rise up against you
Half - Lie - ...
Pankiller - Game about a man, who wants to kill all the pans, because he sucks in the kitchen.
The Pat - A depressing story about a dog, who never got any love in their life
Rabbit Hoe 3D: Steam Edition - ...

Super Eat Boy - A game about a boy made of food trying to rescue his delicious girlfriend.
Sniper Lite - Demo version of sniper simulator
1001 Pikes - A game about catching every fish there is
Lan Wake - Tutorial of how to revieve your server
Arm: Cold War Assault - A game of soldiers fighting only with fists

Pat of Exile: get off this ship, Wraeclast awaits you!

Dadly profits - A father struggles between caring for his disabled son, and going up the corporate ladder to provide for his family. He soon learns what real riches are in life.