Very modular; you can choose a different difficulty for Tactical and change it at any time, there is an extra easy difficulty (Story Mode), a lot of stuff scales with difficulty (e.g. humanoid enemies on Rookie have lower stats, and you can choose at the start of the game how many resources to get, etc. And there is no doom clock in TFTV.

No doom clock is amazing. Thank you.

Playing TFTV now, which feels really good so far for a casual experience - but I've noticed that the structures in the base no longer seem to generate resources. Is it possible to start running out of resources over the course of the campaign (explore nodes run out on the map), or will there be research upgrades in the future that allow for that function?

Fabrication Plants and Research Labs never did produce resources even in Vanilla. There is a mod which does this.
Effective resource management plays an important role in the game. I play with very few bases (in most runs with only 4 or 5) and still have world coverage. Lots of (early) Research Labs are important because late game research is expensive. 3-4 Fabrication Plants are enough. I rely on looted armors and weapons for a very long time (there are exceptions like Goliath Grenade Launcher or Neurazer). Extra airplanes (built not stolen) are needed for early and aggressive exploration.
There is the Food Production structure which produces Food and may turn captured Pandorans into more Food (which then can be traded). But it takes a long time for this structure to break even. It definitely isn’t needed for winning the game.
BTW, I’m used to Legend’s 100% and Etermes’ 75% resource acquisition multiplier. But it is possible to change the default multiplier in the mod options. Choose a value to your liking.

Originally posted by mar.sch:

Fabrication Plants and Research Labs never did produce resources even in Vanilla. There is a mod which does this.
Effective resource management plays an important role in the game. I play with very few bases (in most runs with only 4 or 5) and still have world coverage. Lots of (early) Research Labs are important because late game research is expensive. 3-4 Fabrication Plants are enough. I rely on looted armors and weapons for a very long time (there are exceptions like Goliath Grenade Launcher or Neurazer). Extra airplanes (built not stolen) are needed for early and aggressive exploration.
There is the Food Production structure which produces Food and may turn captured Pandorans into more Food (which then can be traded). But it takes a long time for this structure to break even. It definitely isn’t needed for winning the game.
BTW, I’m used to Legend’s 100% and Etermes’ 75% resource acquisition multiplier. But it is possible to change the default multiplier in the mod options. Choose a value to your liking.

Oh that makes sense. Thank you for the detailed and comprehensive reply.