 Sirians need vertebrate creatures in which to lay eggs to produces new Sirians; this is why the Sirians targeted Earth after searching for a new home planet.Citing the claims on the game's packaging, "Computer Gaming World" stated that ""Mantis" is neither a successor to that 'other' space adventure nor is it an 'Ultra-realistic space flight simulation' ...The flight model is weak, the action limited, and overall gameplay, poor ... a null game."