Tiny-ecs is an Entity Component System for Lua that's simple, flexible, and useful. Because of Lua's tabular nature, Entity Component Systems are a natural choice for simulating large and complex systems. For more explanation on Entity Component Systems, here is some basic info. Tiny-ecs also works well with objected oriented programming in Lua because Systems and Entities do not use metatables. This means you can subclass your Systems and Entities, and use existing Lua class frameworks with tiny-ecs, no problem. For an example on how to use tiny-ecs with object-oriented Lua, take a look at the demo branch, specifically the systems and entities sub-directories.