Here are some rules for using the Dirtside II system to recreate battles from Heinlein’s Starship Troopers.
Explore Alterra is a tabletop RPG that eschews a character sheet in favor of cards that measure spells, weapons, armor, talents and items. It is a very straightforward system, and an interesting setting.
The Heavy Metal Wargaming site has some counters for use in starship games set in the Star Trek: The Next Generation universe.
Here’s a video with advice on building modular catwalks. The techniques also can be used for a variety of science fiction projects.
Wargamer and Teacher Matt Fritz has written MiG Madness, a set of free wargames rules for playing air combat in the Korean War.