Things that instantly "blocked" some games for you.

P2W, season pass crap, hardware requirements ( because I really need a new desktop :P) and game-breaking bugs.
For example I was playing Sherlock Holmes the Awakened ( which is the one with Cthulhu in it) but at some point in the middle of the game after I had finished a big mansion house setting, I was supposed to go back to the city but the game just didn't go. There was nothing to click, no way to leave the map of the mansion etc and I was basically stuck there even though I had done everything right - even redid the area with a walkthrough. I uninstalled it with a heavy heart, because it was a pity. :/

Survival/crafting games tend to need online or co-op for maximum entertainment.
So therefore,it would be pointless for me because I do not like online oriented stuff as of now.(internet problems)

I'll buy a game even if it contains these elements but I won't be too happy with the purchase.
*Edited to explain clearly.

Trying too hard to force a 'moral' on the player. That's a dealbreaker for me.

I couldn't finish the game because I couldn't clear the last stage for some reason. And trust me, there are some pretty disturbing scenes in the game.

Season pass for unreleased games instantly puts game under the radar until GOTY edition or whatever. Also moba.

-Turn-based
-MOBA / Tower defence

"Call of Duty" in the name.
Minecraft graphics and mechanics.
Made by EA.
Has DLCs (unless the DLC is actually a whole separate campaign, or includes features that don't fit in the original game, e.g. Deadliest Warrior for Chivalry, Episodes from Liberty City for GTA IV).
MOBA
Point & Click (nothing wrong with those, just not my type)
NARUTO SHIPPUNDEN SUPER URTIMATU MEGA NINJA WARRIOR STOREMU KAWAII REVORUTIN EXTREME SHURIKEN EDITIN

Games with creepy atmosphere like Silent Hill. I feel like creeping into a corner and cry when I play those kinds of games. No more I say.

For me, it's what follows this sentence that turns me off to games or the idea of buying them, never mind playing.

• Multiplayer Only - Since the move, I have a terrible internet connection without any option for improvement beyond moving again. If a game's only purpose is multiplayer, I'm not going to buy it.
• Multiplayer Focus - In addition to the reason mentioned in 'multiplayer only', games that focus on multiplayer over just playing the game annoy me. If I want to get screamed at by a foul-mouthed ten-year-old whose parental guidance is incredibly lax, I'll go to a shopping mall or elementary school.
• Short Campaign - Nothing annoys me more than a short campaign. I'm not talking solely main quest-line, however. If there's nothing in the game beyond the main quest to hold my focus, I'm pretty much guaranteed to lose interest. Speaking of...
• No Replayability - If a game doesn't have very much content beyond the main campaign, there isn't much room for fiddling about, and no reason to play it multiple times, which limits the reason to even buy it. I want more than just a cheap thrill out of my games.
• Jump Scares - Yeah... Just, it's not scary, okay? No more scary than me cutting off my lips, dropping my pants and bursting from around a corner at you shouting "Oooga booga booga!"

Incidentally, what is it exactly that you are pointing out in that Homefront video? Is it the NK soldiers beating and executing civilians? Sad to say, but historically, occupying forces often went to extremes to 'pacify' civilian populations in places, even if it wasn't officially sanctioned. Beatings, rapes, murder... anything to make the populous realize that they are powerless against their oppressors. If you were suspected or proven to be part of any sort of resistance movement... well, you saw what happened first hand in the area of the video you linked. Though it might be the fact that I'm inured to such things, but I don't see that as them attempting to be edgy; I see it as the developer aiming to give an authentic feel to a bleak setting, as well as making their game somewhat allegorical to the Nazi occupation of Poland. It's supposed to horrify you, because despite what Call of Duty or Battlefield games would like you to believe, there is no glory to war.

To be honest I had actually forgotten that this game had existed after its short disappearance from Steam following the demise of THQ. I'll have to wait to see if it goes on sale, despite its reportedly short campaign.

Multiplayer or co-op games, or games that are single player oriented, but then the developers decide to put co-op or multiplayer in it to please people who say that a single player only game isn't worth the full price.

You shall see the german "translation" of Homefront xD

Sorry, but the game was so derpish and depressing at the same time, that I decided not to decide in which way to play it and more like not to play it anymore.

I don't play racing or sport games. Also, I don't play non-Steam games now [with Diablo being an exception] and I don't buy DRM-free games.

The main thing that makes me stop playing a game is boredom. For example Remember Me bored me so much with its fighting system, that I just switched to play something else.

1. When the game's graphical expression is ugly. Gameplay over graphics, I know I know... It's not about advenced technologies, framerate, resolution... Simple graphics can looks awesome, pixelart can be stunning. I fully respect artist's intention, but please, don't mask your laziness as an 8bit hardcore retro visual when it's not necessary.
2. When the game which is not based on controller gameplay(Brothers: A tale of two sons, Octodad, etc.) keeps telling you you should use it otherwise you are a fool.

World war games or something that is ambiented in a war.

Point and click, just not my tipe of games.

MMORPG/MOBA's.

And from now on, ''Survival open world zombie games''... there are just too many of them now.

When games in a series get more and more "causal friendly". (I.E. Skyrim....)
When new Devs take over a series. (Sacred...)

Achievements from DLCs. AC Brotherhood for the ps3, has some DLC achievements to get 100%. It ruins my achievement count >.>

No local single player mode

Motionsickness

the tags <platformer> or <shmup> usualy do keep me far away

Controls. Whenever I play a game I probably decide whether or not I hate it within 2 minutes of simply moving around. Hammerfight is an example of a game I couldn't stand. Others include And yet it moves, Blocks that matter(controls were pretty annoying but it wasn't what ultimately made me stop playing), Xotic...

Also scary games. I just can't deal with them. I stopped playing The Ball because the atmosphere made me too nervous.

Lastly I have this stupid thing where I actually enjoy playing games instead of watching 10 minutes of exposure. Console games do this far too much, specially in the PS3/4 generation. I love a GAME like say Dustforce; I open the game and it's a game, I play it, it's fun, who cares. Then there's games that take away gameplay just to shove stuff down my throat. Games like Bulletstorm, which I started playing... then I had to sit through and wait for so freaking long, slow walking behind this dude listening to his life story, loading screen after loading screen, just thinking "LET ME PLAY THE GAME ALREADY"... I love good stories in games but there's many ways of telling them. Story through gameplay or while playing but don't try to make me watch your movie which happens to have a game in it.

No nude mods = no buy

I think you have a pretty weak mind...

Here is my list:

1. MOBA, Sports, Strategy are typical game genres I really don't care about. There are some exceptions to this rule though.
2. Bad console port, locked to 30 FPS. Self explanatory, if the devs don't want to spend some time making a good PC port, I won't play their game.
3. Uplay. I bought Assassin's Creed 2 on launch day. That was the biggest mistake in my life, and since then I pirate Ubisoft titles.
4. P2W. I will won't bother with a F2P game if it's just a cash grab. Good games I can think of are Warframe and Path to Exile.
5. Milking a game with tons of DLCs. Specifically I'm talking about The Sims. I love playing them, but I REFUSE to give a single cent to EA. So I pirate them.
6. Always online DRM, if a games has that I will just pirate it. I had enough trouble with Assassin's Creed 2 and I don't want to go trough it again.
7. Call of Duty and Battlefield. Never cared about those games.
8. Multiplayer only. There are some exceptions, but I mostly like to play alone so I usually skip those titles unless they area really good.
9. A low score game. Two things I look at are user reviews on Steam and Metacritic. If the score is too low, I will pass.

That's all I can think off right now. There are probably a few more things, but I think this is a good enough list.