Sports (just not interested)
and MMORPGs (too high addiction potential and not enough time to indulge it)

MMORPG -was never tempted to try
Platformers
Racing games
Games where zombies are omnipresent. A few zombies in a RPG is ok. But hordes of zombies everywhere simply is a blocking condition for me.

Platformers
Racing games (Exception Moto Racer)
Puzzle games
Adventure games (Exception Sunless Sea)
Sport games
MMos
Mobas
Point and Click
Mobile games
Facebook like games
Flash games
Fighting games
All browser games
And all games without a story/campaign.
Sims series

No simulators for me.

Interesting because that is a pretty big field. None of any kind?

I would like to think there are no genres that I just won't try, but there are. Here they are:

Anything best described as indie.
Anything best described as a browser game.
Non Mario or otherwise non interesting sports games.
A game that can be described as a walking sim.

Forgot MMO and online games.

Turn-based strategy / Real Time Strategy - I SUCK
Puzzle - Same as above.
Racing / Simulation / Sports - Just no appeal
Horror - Just the dang pictures give me nightmares.
MOBA - They really don't seem friendly to new people.

Not a Genre exactly, but I tend to avoid first person games. They make me sick more often than not, and since you can't resell PC games...

MMOs / MOBA : waste of time & effort for me

Hmm... RTS I rarely touch, so far only the first Command & Conquer + Red Alert I appreciated...

Anime (Don't get me started)
Fighting
MOBAs

Fighting games. I just never got the hang of them. Excet for Eternal Champions on the Genesis I get wrecked easily.

Oh yeah I forgot about Casual games.

Filthy stinking casuals.

Fighting games like wrestling, martial arts, etc... I can't remember all the button combinations and I am especially too slow to use any defense move.

Racing games that involves realistic tuning of the car.

Non turned based Real Sport simulations.

Too unrealistic flight sims.

I'm too chicken to play horror games but I still buy them because I love horror movies.

RTS where you can't set the speed. The last I was able to play completely was Red Alert 2.

Platformers but there are so many of them that I want to get into them. (I did a thread in the past asking for advices on platformers for non platformer players)

RTS games. I played Warcraft 3 and enjoyed it, but in general it just isn't my genre.

I've never tried the Grand Strategy genre though. I think I just saw it as another type of RTS, but I saw a video of one of the Crusader Kings games recently and it piqued my interest. I think I'll give it a shot if/when I see it in a sale.

MOBAs aren't my thing either. I can't really say I never play it because occasionally friends will drag me into Heroes of the Storm, but it's not a genre I'd just sit down and want to play.

Depending on the game, I may play it because I find it fun even if it is from a genre I typically avoid... like Mortal Kombat.

There's really only one that I don't bother with at all: MMOs. Waste of time and money.

Adventure games. I feel like smashing my computer to pieces and throwing it out the window from all the walking around with no clue what your supposed to be doing.

Working out what your supposed to be doing is not gameplay in my opinion. But that's just me, a lot of people love them.

Multi player shooters - I mean how many times do you need to shoot at something. Duh! I shoot you!

No desire to go near hidden object games.

Also fighting games, I dislike the idea that all you can do in the game is fight in a small area. Fighting stuff through levels with a story is fine though, like Ninja Gaiden or Naruto.