Where do I even start?

Personal projects?
So many. Shouldn't count.

Unpaid game dev intern?
Unpaid game dev volunteer?
Both worthwhile, if stressful. Shouldn't count either.

Freelancing where clients refused to pay?
That's happened a few times. One of them paid me in product instead of cash (WonderSoil, a company that [apparently still] makes and sells some expanding super potting soil thing). The product turned out to be defective and killed all of the plants I used it on. I'd have preferred getting stiffed instead. Their "factory" (small, almost tiny) was quite cool. The owner was a bitch. Probably still is.

Companies that have screwed me out of pay?
So many. I still curse their names at least once a month. I've been screwed out of about $13k now, maybe more. I've lost track.

I have two stories in particular that really piss me off.

The first: I was working at a large robotics company, and mostly enjoyed my job, though the drive was awful. The pay wasn't high either, but I still enjoyed the work. Schedule was nice, too: 28 hours (four 7-hour days) per week. Regardless, I got a job offer for double my salary, same schedule, and the drive was 11 minutes instead of 40. I took it. My new boss ended up tricking me into being a contractor -- refused to give me a W2, no contracts, etc. Later, he also increased my hours to 40 with no pay increase. He also took forever to pay (weeks to months), and eventually refused to pay me to my face, in front of my cowokers. Asshole still owes me about $5k. Should owe me the the difference in taxes, too (w2 vs 1099) since he lied about it and forced me into it when it was too late to back out.

I talked to the BBB, the labor board, legal council, the IRS (because he was actively evading taxes), the fire inspector (because he installed doors taht locked if the power went out, installed the exit buttons on the fucking ceiling, and later disconnected all of said exit buttons). Nobody gave a single shit. Asshole completely got away with everything. Including several shady as hell things I can't list here because they're too easy to find.

The second one:
The economy was shit, and I was out of a job. I had been looking for quite awhile, and an ex-coworker (who had worked at google, interestingly) suggested I work for this new startup. It was a "reverse search engine," meaning it aggregated news and articles and whatnot, and used machine learning to figure out what its users are interested in, and provided them with exactly that. It would also help with scheduling, reminders of birthdays, mesh peoples' friends' travel plans and life events, etc. (You and a friend are going on vacation to the same place, and your mutual friend there is having a birthday! You should go to ___ special event that's going on while you're all there! Here's a coupon.) It was pretty cool. The owner was not. He delayed my payments a few times, and screwed me over on pay a few more times, despite promising me many times that he was "not one of those people." He ended up paying me less than fucking minimum wage. Fake, smiling, backstabbing asshole.

The first one still pisses me off more, though, because of all the shit I went through trying to get my missing back pay, and how he conned me every chance he got. And how he yelled at me and told me, to my face, that he wasn't ever going to pay me. Fucking goddamn hell I hate that guy.