The first "real" game I published online was Fast and Dirty (FAD). Originating as a scrappy PDF exported directly from libreoffice, it nevertheless found a small following online in the days of Yahoogroups. The game happened to more or less coincide with the boom in 15mm science fiction which meant there was an audience looking for something that let them use any figures they could buy.
The inspiration for FAD was very much Stargrunt 2 (SG2), though some aspects were things that I had been mulling over in various games me and my friends had experimented with but which had never been published. I wanted to take a lot of the same elements Stargrunt had (particularly suppression and dealing with casualties) but make them a bit smoother and faster to handle. The end result was a game that didn't really have any specific rules element in common but which clearly pays homage to the concepts of SG2.
One of the key features of FAD is the "Under Fire" mechanic. At the time I was intrigued by suppression mechanics in games but I didn't like how in most games it was an all or nothing affair. The Under Fire rule was one of the first things I wrote down on my notebook and it would remain mostly unchanged in function through 5 editions of the game: A unit that is shot at is always marked Under Fire and is then limited in its ability to move and fire.
This gave me the result I wanted: Units cannot be shot at without reacting in some manner, but they are never completely immobilised or prevented from acting.
Everything else kind of fell into place around that basic idea. Some elements such as dealing with wounded soldiers, armor rolls being an opposed roll and troop quality affecting weapon range came from SG2, others such as quality determining which units you can shoot at were my own creation. The idea of using 2D6 and picking the highest for combat came from playing the 1916 and 1943 wargame rules (by the War Times Journal) and liking the idea of a single roll determining the amount of damage, but disliking that it was so random.
A few people have asked if the morale check mechanic (rolling 3 dice and counting successes) was borrowed from Chain Reaction (which hit the scene at the same time) but I didn't play Chain Reaction until a few years later. The inspiration for the morale checks came from my experience with the White Wolf role playing games instead. In hindsight morale could probably have been reworked to just use a simpler approach but the idea of unified dice mechanics was not something I was invested in at the time.
One innovation that I was proud of at the time but probably would not have done today is how traits were handled. I got the idea that a particular ability, such as moving through terrain with no penalty, would be more valuable to a strong unit than a weak unit and so all traits were given a cost multiplier. This worked pretty well, but was a bear to manage for army building ("okay so this unit is 37 points times 1.2 times 1.4 times..) and caused weird problems when one player took a lot of traits and the other didn't.
The game succeeded in carving out a small but surprisingly loyal audience and I still receive an email or two from people every year saying they remember the game or just started playing it again after years of break. Considering how rough those early versions looked, that is pretty amazing. I suspect that the game leaning into the "hard military" vibe which has always been a bit of an underserved niche in sci-fi miniatures probably helped.
In total there were 5 editions of the game. The first is unfortunately lost to time but did feature a fair bit of original artwork by a gentleman who offered to draw up a whole bunch of illustrations for me as a favour.
The second was a revision of that, featuring a lot of additional rules but unfortunately lacking artwork except the cover picture of the soldier with the katana.
Third edition saw the help of Steve Green who was a fantastic help in both revising the rules and giving the game a proper layout. this is the "army edition" which featured photos of modern military troops, with photoshop filters over them, since we did not have any proper artwork available. This was also a pretty big overhaul of the game rules.
Fourth edition is the last that was available online and featured a number of additions and changes, as well a host of original new artwork provided by the folks on the Yahoogroup. This is the "power armor" cover.
A fifth edition was released on the Yahoogroup but was not available otherwise. It featured my planned additions to the game, particularly regarding vehicles.
In the final years of FAD, I struggled with what to do with the game. In particular, I had pondered putting it under an open license but the process seemed rather difficult and I had a hard time justifying spending a lot of time on the game, compared to writing material that I would be able to sell. As I left the rules alone, they mostly fell by the wayside and Yahoogroups would eventually fall to the cold hand of internet decay. Eventually a gentleman reached out and offered to buy the rules from me, which I agreed to.
In a lot of ways, FAD is the game that lays at the foundation of everything else. Without that game and the boost of confidence it brought, it is perhaps doubtful if any of the subsequent games would have ever been created.