Needle and Bone

A solo real-time duel between Hornet and Sans, built from your installed copies of Undertale and Hollow Knight: Silksong on Windows. Both games are required. Undertale stays the primary game; a dedicated Silksong companion supplies Hornet’s real controller, animations, skills, tools and crests to one visible encounter window. Game artwork, voices, effects and music are read from your own copies, never included in the download. Original game saves are not loaded or changed.

An animated, skippable sepia prologue introduces The Last Thread: a fracture is erasing Hallownest, and Hornet’s plan to sever its temporal anchor threatens Sans’s home. Walk through the Judgment Hall, rest at the bench, choose your equipment and speak with Sans. The hallway keeps its shadowed Sans, foreground pillars, fractures, silk, distant arches, light and dust. Hallway music stops for the conversation. Important conversations and choices wait for you; combat chatter keeps the action moving.

Fight through three waves with Hornet’s native movement, needle, pogo, dash, silk skills, Clawline, Needolin and active tools. Sans moves and jumps between available surfaces, throws bones and movement-sensitive blue attacks, swings a held bone, changes gravity and aims Gaster Blasters with visible warnings. Ground attacks temporarily remove elevated platforms. Crack marked bones to open a route and leave temporary silk rings for native Clawline interactions. Sans reacts to repeated pogos, tools or heals. Four final-wave corner blasters can be destroyed; defeated blasters lose their solid bodies. Cut three silk seals in time to cancel a late aimed blast. Talk/Challenge and a late mercy choice lead to two endings; no practice mode.

The bench offers skills, crests, three unique active-tool slots, native tool icons, remaining charges and three saved loadout presets. Every three confirmed hits restore one tool charge, and every five Sans hits restore two masks; hits also restore native silk. Consecutive hits trigger a warned harmless push. A victory summary records time, hits and damage, with local personal bests by difficulty and ending, rematches and unlockable Hard mode. Reduced motion, volume controls, fullscreen/window switching and Silksong’s saved controller bindings are supported. Keyboard shortcuts remain available; controls reconnect after a device-reader failure.

0.10.16 corrects Undertale store-folder discovery, installs the bundled loader into Silksong and launches that companion directly, avoiding Steam’s extra launch confirmation. The dedicated Silksong window stays hidden while Hornet runs inside the mashup. Controller reading is isolated so a driver failure can release input and reconnect while the duel stays open. Historical SDL crashes lacked a native stack, so this is a containment fix rather than a proven diagnosis of every crash.

Credits: Undertale by Toby Fox; Hollow Knight: Silksong by Team Cherry. Original mashup story, presentation and integration created with AI assistance. New project code is MIT; remixes are allowed. Original game content retains its owners’ rights. Runtime and loader credits/notices accompany the download: CPython, pygame-ce, Pillow, PyInstaller, BepInEx, HarmonyX, MonoMod, Mono.Cecil and Unity Doorstop.