Romance of Three Kingdom 8,9,10,11 with my PS2 Emulator, 8 and 10 for RPG-esque Strategy Game (played as mediocre officer and training until all stats and skill maxed, became legendary officer XD), 9 for fun random city search event, and 11 for interesting Turn-Based Grand Strategy (and destroying larger enemy armies by dueling and capturing their general :p )

Not a guilty pleasure, at least not according to some bum-fodder game-mag. or "journalist" ...
but at a certain game time it might me considered as such.:

HAWKEN > this is what the gameplay on a faster mech looks like if you're great - all in all with the selection of Mech
its incredibly satisfying. Tried playing instead (~22hrs) Titanfall but that piece of Garb had too much COD in it.

If I'd feel guilty about playing and enjoying a game that not many seem to hold in high regard it would probably be Two Worlds

Edit: After reading through this thread I feel like the concept of guilty pleasure is lost on many of it's contributors but it may also be that I have it completely the wrong way

A lot of games in the Party genre, especially ones on the Wii. They can be really shitty a lot of the time, but I can almost always have fun with them when playing with friends.

Far Cry 2 and Miasmata, and the first Watch Dogs, hated by a lot of people but i enjoy it much more than gta5.

Dark Gates. It's a crappy little turn-based, party-based dungeon crawl. But I'm a sucker for those things and played for 12 hours and got 100%.

league of legends :(

Resident Evil 6

HuniePop ( ͡° ͜ʖ ͡°)

TF2 :D

Probably Dragon Age II. I dont feel guilty but people seems to dont like it and I think its the best DA game...

FF8 :)

For years now, mine has been Soldat (https://soldat.pl/en/)

Batman arkham knight on low ;-;
and lego games

Lego Whatever. Brainless collect-a-thons really, but once I fire one up I can't put it down until I've 100%'ed it.

Versus Squad

Trace Vector

Guns of Icarus Online

Mountain

AC 3
people always told me it was the worst, but I liked it a lot

Justget10

Minesweeper :)

AC: Black Flag

because it has nothing do with AC, but it's incredibly fun!

Genital Jousting. Oh wait, did you mean a video game?