There'll be very little running away; in fact, to have a decent chance of coming out on top, you'll have to run toward them! (Also known as tactical maneuvering
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If you can spare the time to try them out, you'll discover quite a variety of missions: Some set-piece encounters, some whirlwind battles. Some require stealth and speed, some are straight slug-fests. Some require coordination with friendly units, others let you be a one-man army! But taking the indirect approach often helps!