Watched The Tomorrow War on Prime last night. Basically a sci-fi version of a zombie movie. The enemy is toothy aliens with tentacles, always coming in great numbers. Heavy weapons smash them up just fine, and even assault rifles can work if you fire enough from the much longer than they look clips. The aliens have no weapons beyond their many many teeth, some nasty projectiles that shoot out the end of their tentacles, and their ability to throw and smash things (they are strong, and great jumpers.)
Still, since they have little in the way of action-at-a-distance weapons, and no anti-tank or anti-aircraft stuff, I can't figure out how they have wiped humanity out except for a remnant of 500,000. Must be magic reproduction, they ate billions of people, and so nourished, made billions more aliens. So, like I said, the zombie idea, just a little more biological about it.
At start of movie, some future soldier guys make an entrance at the World Cup, and inform everyone how crappy things are going just 30 years in the future. A good strategy immediately came into my mind, but not seemingly to anyone in the movie. Future guys instead proceed to suggest that the present send them infantry, they can take about 1000 at a time it seems. Doesn't seem like it would work. It doesn't, though it does occasion a lot of hairy fighting for our brave and gritty heros.
Ultimately a strategy along the lines I thought of initially (with a few twists) is implemented, and the Earth is saved. Great movie if you like seeing rough tough humans tear up alien monster guys, even when it seems impossible. There's a bunch of that.