Modernizing NetHack's C engine with .NET MAUI, Avalonia and a 31-tool AI advisor

Sound Mind Games (Hyvän mielen pelit ry), a Finnish nonprofit, describes how GnollHack wraps NetHack's roughly 500,000-line C99 engine as a native library behind a shared C# client, migrated from Xamarin.Forms and SkiaSharp to .NET MAUI by April 2025 and extended to Linux, the Steam Deck and macOS in 2026 via Avalonia.Controls.Maui. The game's opt-in Gnoll Overseer advisor embeds a web app that reads live game snapshots from the C engine and uses 31 tools (20 server-side, 11 on-device) to look up facts, and GnollBench grades models with the production prompt and tools using a blind two-provider judge panel, a geometric-mean score, a 25-point critical-error cap and a 50-point honesty floor. The post also covers the October 2026 nine-model benchmark results and the team's agentic workflow, in which coding agents write most C# and TypeScript code while the C engine, art, music and voiceovers remain human-made.