I was on swfchan.com and got curious to see if they had anything Guro-related, and found some decent stuff, and some crappy stuff.

Stuff I like/found interesting:

http://eye.swfchan.com/flash.asp?id=152464&n=Nai+by+tlaezotilli.swf - Short Hypno Guro Slideshow

http://eye.swfchan.com/flash.asp?id=97933&n=Dr.Choker_Surgery_guro_fun.swf - Basic Head Fuck Game

http://swfchan.com/4/19761/?guro.swf - Classic, The Torture Game

http://eye.swfchan.com/flash.asp?id=23333&n=Studio+S+-+Mesubuta+Choukyou.swf - StudioS Torture Game

http://eye.swfchan.com/flash.asp?id=23007&n=Studio+S+-+zettai_seido.swf - StudioS Torture Game With 2 Girls

http://eye.swfchan.com/flash.asp?id=24712&n=Studio+S+-+ero05_02.swf - Another StudioS Game

http://eye.swfchan.com/flash.asp?id=20465&n=bs_fl_03.swf - Even more StudioS Games

http://eye.swfchan.com/flash.asp?id=20323&n=bs_fl_02.swf - More StudioS

http://eye.swfchan.com/flash.asp?id=20310&n=titty+puncher.swf - StudioS

http://eye.swfchan.com/flash.asp?id=1508&n=brainfuck.swf - Short Brain Fuck Game

http://eye.swfchan.com/flash.asp?id=103208&n=a01.swf - Loli Necro Loop

There's a lot more to discover, which will be something I hope you enjoy, if you have any other good guro .swf files, please share.

You can type Guro on the search bar and get a few results, it's best to search on the Pain category: http://swfchan.net/categories-pain.shtml