Extract from the designer's notes :Space Marines is a game designed to simulate land combat in the interstellar era. It is a game based on small unit operations so that large battles cannot take place within the context of these rules. [...]There are two different scales used in Space Marines, in effect, there are two different games here. The basic game uses a time scale of twenty seconds per turn and a normal ground scale of one inch equaling twenty-five meters. In the 'skirmish' rules the time scale is ten seconds per turn and a ground scale of one inch equaling 12.5 meters. The basic scale assumes that the players will have a significant number of figures on the table, possibly ten to twenty per player. The skirmish rules are intended for very small numbers of figures per player, no more than two or three under normal circumstances. The skirmish rules are almost entering into role-playing, although they do not constitute a full role playing system, just a combat system. [...] - BoardGameGeek