Trench Defense
They don't stop. They don't sleep. One trench, a few towers, and your nerve.
The enemy's coming. They don't stop, they don't sleep, and the only thing between them and everything behind you is one trench, a few towers, and your nerve. Dig in with WWI machine guns, dig out with future-tech turrets, and hold the line while the AI probes every weak point you left it. Pathfinding enemies find the gap. Status effects stack. The next wave is always worse than the last. I'm building this one with my kid, which makes it the most important thing on this list, the game's half of it, the building it together is the rest.