I'm working on several tabletop RPGs at once right now. This post is meant to keep my thoughts straight on what each one is meant to achieve and how it plays differently from the others. Hopefully, that will prevent them from all blending into variants of each other.
Ingenium Second Edition
The digital whiteboard Miro has been invaluable in working on this lately. I have virtual post-it notes all over the thing.
Ingenium Second Edition (I2E) is my personal flagship. The system is an evolution away from the swingy, explodey mechanics of the original into a math-flat system that encourages interactions beyond just combat. With twelve attributes, 2d6-based rolls, flexible magic systems, and very limited bonuses, it's a highly controlled system.
The setting is influenced by simulationist ideas of injecting realism into the various parts of the game world, but still has many of the same roots of the original implied setting. This includes imminent war, an overarching epic plot, and ancient evil.
Mysteries of a Broken World
Mysteries of a Broken World is a post-apocalyptic fantasy game. Originally it was meant to be Silver Gryphon Games's entry into the OSR field. SGG folded before that could manifest, and I later brought MoaBW under my own development.
The system is meant to hew closely to the ideals of old-school gaming: there should be few rules, the combat should be lethal, and the stories should be pulpy rather than realistic. However, it adds the wrinkle of throwing in survival game mechanics, to make the environment a deadly adversary also. There may also be an element of base-building involved; this is still very much in the theory phase right now.
The setting is post-apocalyptic fantasy. The world-that-was either was modern day Earth or something quite like it, but that was long ago. Now it's rampant with strange forces and stranger creatures. There is no overarching plot and no epic story.
Vox Draconis: Kingdoms of Stone and Fire
The spiritual sequel to the original Vox Draconis has a new setting and a new game system. The original game was very much a copy of Dungeons & Dragons Basic with the serial numbers filed off.
VD:KSF's system is focused on the player characters as heroes who affect the game world. Like I2E, it's less about killing monsters and more about having an impact. Unlike I2E, there are fewer rules and less customization. Most mechanical choices happen at character creation. It uses a d20-based roll-over main dice mechanic and relies heavily on player creativity.
The setting is somewhere between the Stone Age and Tolkienesque fantasy. The world is less advanced than average fantasy, includes dinosaurs alongside dragons, and generally favors a whimsical approach to setting blending. It's not grimdark or gritty, and encourages players to imagine the best.