The Binding of Isaac: Antibirth

This is a substantial, free fan-made Mod released in 2016 for PC, significantly expanding the base roguelike shooter experience. You navigate procedurally generated levels, fighting enemies using twin-stick shooter mechanics while collecting items that build unique RPG-like synergies. Its core appeal is the massive injection of new content, including fresh characters, items, enemies, and secrets, offering veteran players a deeper, challenging continuation of the dark basement descent narrative.