Microbial mats including cyanobacterla, and in particular desert cyanobacteria, probably genetically engineered to Improve some of their capabilities, may play a crucial role in the terraforming of Mars, as part of wider ecosystems and providing a range of ecological services including but not restricted to the production of oxygen, encompassing also the production of greenhouse gases, the creation and fixing of soil, dust amelioration, providing the foundation of trophic pyramids, and psychological benefits to settlers from gardening and landscape variation. Cyanobacteria have evolved on Earth, where they prompted the GOE (Great Oxidation Event), to survive and thrive facing some of the key environmental challenges awaiting them in the Red Planet, Including high levels of ultraviolet radiation and radical temperature shifts. Present-day Mars resembles pre-GOE Earth on many counts. To date, some key experiments have already established the resilience of cyanobacteria such as Nostoc sp. to Mars-like conditions, and this has been supplemented by theoretical models and studies involving other species such as Chroococcidiopsis. However, much more research is needed before we can state beyond any reasonable doubt that these promising characteristics can be translated into practice. Future research should focus on ecosystems, not single species, and experiments should gradually move to ideally reflect actual real conditions, including the presence of mutually supportive microorganisms, extracellular substances (such as EPS, extracellular polymeric substances), and mineral grains, sand, or cobbles, as are sometimes found in terrestrial deserts, until, finally, viable microbial mats are tested In Mars-like conditions.