IsaacKill

ULTRAKILL × The Binding of Isaac. Play as V1, with all of your ULTRAKILL movement, guns, parries, blood healing and style, through a generated Isaac run in full 3D.

Pick THE BASEMENT on ULTRAKILL's main menu and drop into a generated floor:

• 10 floors: Basement, Cellar, Caves, Catacombs, Depths, Necropolis, Womb, Utero, then Sheol or Cathedral, then Dark Room or The Chest. Each floor has its own walls, rocks, lighting and music.
• Isaac rooms: doors lock until a room is clear; treasure rooms, a hidden secret room (blow open the cracked wall), and a boss room with a trapdoor down. Cleared rooms can drop red hearts.
• Over 100 Isaac monsters and bosses as 3D voxel models. Each has its own telegraphed attacks and punish windows: Gapers lunge, Attack Flies dive, Hosts hide under their skulls, Masks are armoured from the front, Dople mirrors you, Globins reform unless you finish the pile. Bosses include Monstro, Duke of Flies, Larry Jr. and other worms with segmented bodies you can shoot, Gurdy, Peep, the Horsemen, Mom's stomping foot, Mom's Heart, Satan, Isaac, ??? and The Lamb.
• Isaac items that change how V1 plays: Brimstone blood laser, Polyphemus mega shots, Inner Eye triple shot, Ipecac explosive shots, Spoon Bender homing, Holy Mantle, Dead Cat, Transcendence glide, Mom's Knife punches and more. Each item shows its real Isaac name and pickup quote.
• Devil and Angel deals after bosses: Devil items cost health.
• Isaac's HUD: red hearts for V1's health, your items and stats, the room minimap, all in Isaac's own font.
• Enemy shots are real ULTRAKILL projectiles you can parry, and your hits draw blood for healing as usual.

Needs: ULTRAKILL and The Binding of Isaac: Rebirth (base game; no DLC needed). Nothing from Isaac is included in this download: every sprite, sound, song and name is read from your own installed copy of Rebirth while you play.

Single player.

Credits: made with BepInEx. Isaac archive reading adapted from Gibbed.Rebirth by Rick (zlib license). OGG music decoding by NVorbis by Andrew Ward (MIT license). Built with AI assistance (Claude).