When I first started working on Neo*RPG, I was trying to create an action RPG engine. Little did I know, by addressing all poor game design issues I had with existing action RPGs, Neo*RPG turned out to be more of an action game.
I started simple with a player, an environment, and an enemy. As I play tested, I looked at the forms and mechanics in the game and tried to make everything as realistic, logical, and as clean as possible. In this case, realistic and logical developed into a governing principle that I now refer to as form fits fuction. My understanding of game mechanics, clutter, and form fits function wasn't nearly as developed then as it is now. However, by simply paying attention to honest feedback, and always believing that there was a better design possible, I intuitively developed a solid game according to tenets of Classical game design.
Just like how Super Mario Brothers proves to be better designed than the vast majority of games next-gen or otherwise, the depth of Neo*RPG's gameplay has become a pillar of my gameplay defense. If I can make a game in 3 weeks that is cleaner, follows form fits function more closely, and is deeper than professionals can after years of development, then there is definitely something wrong with the current state of videogame developers.
But don't just take my word for it. Neo*RPG is always available for download in the side bar under the "Downloads" section. Play it for yourself, and then check out this interplay chart. Much of the interplay in Neo*RPG goes to level 5 easily. As the branches grow and intersect, they also loop back upon themselves. In other words, the interaction from the interplay is tight in a way that keeps every possibility connected to each other in one way or another.
If you want a challenge, try mapping out the interplay of a game of your choice. If you do, feel free to send it to me.