This review paper summarises the current state of digital simulation methods used to analyse human behaviour in physical environments. It aims to identify why digital simulations of human behaviour are not yet commonly used by architects and urban planners and to provide a systematic review of available methods, software tools, their capabilities and limitations. It covers physical models, Space Syntax, virtual reality and dynamic simulation methods for pedestrian and occupant models. There are a number of most common decision-making processes for pedestrian and occupant models. Rule-based process involves predetermined rules or heuristics. Markov Chain uses probabilities and the current state to determine state transition. Goal Oriented Action Planning chains predefined activities to achieve a specified goal. In Narrative-based modelling a narrative governs agent behaviour. In Game-theoretic approach interactions are modelled as a game. Reinforcement Learning involves learning through rewards or punishments and Artificial Neural Networks learn from data and make predictions based on that learning. Although Artificial Neural Networks come with many benefits, such as high flexibility and the ability to handle uncertain and incomplete data, it is a relatively new field of research and it requires significant computational resources. Each process has its own strengths and limitations. Multiple algorithms or decision-making processes can be combined to achieve the desired simulation properties. There are multiple digital simulation software tools for pedestrian and occupant simulations. Some of them, such as SUMO, Aimsun, and MATSim, are optimised for transportation simulations but are not suitable to become auxiliary tools in the architectural design process. PathFinder is a software for simulating evacuation scenarios. Anylogic is a flexible user-friendly tool suitable for a wider range of applications. Tools like IES and CitySim are used for building performance optimisation. A game engine Unity is a suitable option for creating interactive and visually appealing models, however it requires programming knowledge. A simulation in a 3D environment is more complex and requires more computational resources, but it can bring more realistic results compared to simulations in 2D. The paper concludes with discussion about the reasons why digital simulation has yet not become a common tool in architectural practice.