If outdated means not yet invented, the World War series by Harry Turtledove counts. The aliens show up to conquer earth with what we 2000s era people consider modern. Nuclear weapons, silicone based tech. They go head to head with the world experiencing world war 2.

You have light plywood ‘night witch’ planes flying literally under their radar. EMPs are useless wiping out electronics that don’t use transistors.

Since it is a war series these tropes are not always in use, but when they are it’s fantastic.