Can anyone recommend a good tabletop game for modern-to-space opera technothriller in the vein of X-Com or Terra Invicta? For a brief moment of insanity I considered Alternity and then I just reread Alternity.

definitely NOT inflicting that on my players.

The modern book, NOW, for What's OLD is NEW is designed for military thriller without being too mechanically grimy?

The Fall of Delta Green or Night's Black Agents are also a pretty good choice if Gumshoe is going to mechanically support the kinda story you want to tell.

Conspiracy X if 90's RPG design sensibilities, good and bad, isn't a deal-breaker.

Eclipse Phase if plunging into the deepest darkest recesses of math hell this side of HERO isn't anathema to your group.

"90's design" is a good summary of why I'm not using Alternity.

Conspiracy X is basically Mage the Ascension's Technocracy, but running on the Buffy the Vampire Slayer RPG engine, it's a hot mess but immensely charming, but yeah. It's a checklist of 90's TTRPG design tropes, avoid it in this case.

NOW claims that you can download a 12 page preview but the link doesn't work.