Marcus was until recently a distinguished engineer with Callaghan Innovation leading their development of medical devices with a focus on technology to assist neurorehabilitation; principal investigator with the Med Tech Centre of Research Excellence. He created systems such as the AbleX stroke rehabilitation and the Exsurgo Phoenix as well as Virtual Reality for rehabilitation with MTech Games and recently working on NeuralXR for traumatic brain injury with Laura Fergusson Trust and University of Otago. He was NZ Engineering Innovator of the Year in 2011, awarded the Royal Society Cooper Medal in 2010 and the Rutherford Bronze medal in 2001.