Ashen Watch

A one-screen siege that never ends. You are the guardian in front of a keep, waves come, and after each one you choose a perk — arrow volleys, chain lightning, a flaming blade, a dodge roll — so a run is defined by the four or five choices you made early. Eight enemy types and bosses, coins banked between runs for permanent upgrades, and a difficulty curve that is steep enough to make the perk choices feel like decisions rather than treats. Ashen Watch does a lot with one background.