SC2 combined action and adventure with liberal doses humor to create a game now regarded with profound respect by many loyal gamers. SC3 is an adventure. Players travel the galaxy, gathering items, talking to aliens and solving puzzles. More importantly, SC3 has non-linear puzzles. Players will not feel strapped to confining rails found in traditional adventure games.
Some events are linear, but many quests can occur out of order.
In most game situations, players respond as they see fit. Should a star implode in a nearby system, a player checking the system makes sense, but is not required. However, some Lucas Arts puzzles were not intuitive to me. For me, non-intuitive puzzles are the anathema of adventure games. Indeed, all the puzzles in SC3 make sense, in a wacky Star Trek techno- babble way, of course.