I have created several custom game systems for RPG Maker MV. I made a system for a board game, one for a chess game, one for super tic tac toe and my largest project so far, the system behind my card game.
I also create a detailed clock and calendar system, which does keep track of in game time. It comes with seasons, day/night cycles and time based (de)buffs, like being rested, tired, hungry and thirsty. And much, much more. I shared this project as a tutorial, for other RPG maker users to learn from.
I also created a plugin, which does the exact same thing as the system tutorial project, only than it is all plug-and-play, and can be added to any project in minutes. This is currently my most popular project. This project is still receiving regular updates.
If you got curious about my projects, you can find my work by clicking "Games" or "Plugins" on the top of my website. If you try them out, I would love it if you leave a comment. Let me know what you think about my creations.
Have fun!