In games that are meant to be some sort of simulation, the on/off nature of player turns can cause problems and has led to a few extra variations on the theme. The semi-simultaneous turn allows for some reactions to be done during the "other" player's turn. The impulse-based turn divides the turn into smaller segments or "impulses" where everyone does "some" of their actions at one time, and then reacts to the current situation before moving on to the next impulse (as seen in "Star Fleet Battles" or "Car Wars").