I think game trailers are an interesting creative undertaking, and one I've participated in producing quite a few times, so I'll comment on this in-depth.
First, know your goal: A game trailer isn't for players who play the game already. It's for potential players who
may buy the game. And it's got to fit into about 90 to 150 seconds "because that's the way it is", short-form video is the expectation and tradition. Doing video documentation of the depth of a game mechanic is irrelevant to the requirements of a first-sight trailer compared to simply expressing how the game feels. (Diving deep into combat would, however, be appropriate for a supplementary promotional video if such a thing was desired. Some studios find video production really easy, some don't. Alex isn't a guy with native video skills and neither am I, so any video marketing is non-trivial effort/cost due to going through an outside contractor.)
Right, so you've got two minutes to show what the game is about. The most straightforward approach to doing this is to hit on the so-called "game verbs". In other words, explain what you - the player - does in the game. EXPLORE. TRADE. DESIGN. FIGHT. You know, all the good stuff. And show how it feels to do it. Note that there's a very important distinction between expressing "how it feels" and "show exactly how it works in comprehensive unedited real-time documentation". You simply can't do the latter because there's no time and it destroys pacing; the rhythm of watching a 2 minute video and playing an N hours game are completely different. Again, if you want to show the latter in comprehensive form, a valuable and worthwhile move, then that goes into a supplementary video about gameplay.
Indeed, combat is the aspect of Starsector that is the most exciting and shows itself off in video the best so it's got to be the climax of the video. Cruising around planets also looks pretty good, but it's not particularly given to exciting moments like landing a spread of Reapers home on an enemy capital ship. So by necessity the other features come first then the combat scenes build to a climactic explosion last. It's just so structurally easy and powerful to do it that way given the material at-hand.
To review, a primary promo trailer must:
- Be short and to the point
- Express how the game feels
- Show the major game verbs
- Build up an exciting arc to a climax and release that tension in a way that makes the viewer excited about the game
Any primary promo trailer for any game (that doesn't have an enormous presence/marketing budget to do something different) will more or less follow those points. Supplementary trailers may be made that focus more on some sub-point, like a particular game verb, or character, or deep look into an aspect of gameplay. But those all come later, if at all.