In 2008, when I had just started working in animation, a German collector approached me. He told me he had recently purchased a rare prototype cartridge of a fully finished, but unreleased Super Nintendo game called Nightmare Busters.
Nightmare Busters was, and still is, a typical 90s, tough-as-nails run & gun-type platformer in the vein of Contra. Its twist is that rather than gritty sci-fi mercs butchering alien invaders it features two leprechaun characters using magical trinkets to blast their way through a colourful horde of stock fantasy minions and villains.
The game featured for its time above average-looking 16-bit graphics and impressively large sprites. Having had the chance to play it, I can say it's a worthy game of its era, playable and very challenging later on, yet not unfair.
Aforementioned collector commissioned what he called "a 90s-style video game cover" illustration from me for an article he was going to write to be published in a Japanese video game magazine. Since at that time only the prototype existed, no publicity artwork for the game was available, hence the need for some non-pixel artwork. So based on screen shots he sent me, I came up with this:
(Yikes, the "joys" of looking at old artwork from more than five years ago ...)
I have no idea whether the article was ever written, but I suppose it must have because some months later I saw a fully produced reproduction Super Famicom cartridge. The collector revealed to me that the Japanese magazine had those done to give away in a sweepstake accompanying his article.
It's really quality stuff with high-res box art and cartridge prints and even a manual. I was amazed. Only twenty or so of these unofficial cartridges were produced and they used to fetch prices around €400 on ebay some years ago.
During the following years, other unofficial releases appeared on the market - some of which even ripped off elements of my "original" (unofficial) illustration.
An unauthorised rip-off of an unofficial release of an unreleased game. Mind. Blown.
I even came across stuff like this, although I believe this is fan work rather than anything unofficial or illegal.