Have you looked into Strike! RPG? Setting agnostic tactical combat on a grid heavily derived from dnd 4e but with all the fat stripped, leaving a very light, low-math, simple to run combat with a ton of depth but low number crunching. All that is paired with a narrative system that's very intentionally kept light and with intent to get out of your way.

If you're looking to run something where the PCs are a crew of specialists with distinct roles, this might be worth considering.