If you loved Highlander: The Source, try Starship Troopers 2: Hero of the Federation
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
You already loved

Highlander: The Source
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Starship Troopers 2: Hero of the Federation
What they share
Theyboth carry the 3am cult mood tag, and they sit in Action / Adventure territory. If that's the register that drew you to Highlander: The Source, the second film will land in a comparable space — through a different lens.
3am cult
What Starship Troopers 2: Hero of the Federation is
Planet P, near dusk, a low whine. Soldiers barricaded, awaiting rescue. One officer, changed. Tippett's direct sequel is a tidy siege picture.