Opus 5.5 Just Took Over Unreal Engine

Summary Game development YouTuber Gorka Games demonstrates building a playable Dark Souls-inspired action game in Unreal Engine using Anthropic's Claude Opus 5.5 connected via the NeoStack AI plugin and Claude Code. Through natural language prompting, the presenter directs Opus 5.5 to build AI enemy behaviors, a target-lock mechanism, health systems, combat combos, dodge abilities, procedural 3D models in Blender, and complete dungeon arena level assembly.

What is shown

• 00:04 — Terminal-Bench 4.0 leaderboard graphic showing Claude Opus 5.5 at 66.4% accuracy, ahead of GPT-6 Astra (57.5%), Claude Fable 5.1 (54.3%), Claude Opus 5 (52.3%), and GPT-5.6 Sol (31.4%).
• 01:33 — NeoStack plugin UI and the UE 5.8 AI Agent Benchmark leaderboard comparing NeoStack against Epic MCP, Aura, UE Copilot, and Nwiro.
• 02:12 — NeoStack Agent in-editor window inside Unreal Engine, configuring model selection (Claude Opus 5.5), mode (Auto), and effort (Extra High).
• 02:40 — Prompting Opus 5.5 to create an enemy AI that patrols, detects the player, and attacks, which automatically generates blueprint code, behavior logic, and places a NavMeshBoundsVolume in the level [03:05].
• 04:14 — Prompting the creation of player and enemy health components, damage logic, and overhead UI health widgets.
• 04:58 — Generating a stylized 2D concept sheet of dungeon props in ChatGPT, then feeding the image to Claude Code via terminal to model 59 assets automatically in Blender [06:30, 12:40].
• 08:41 — Implementing a Tab target-lock camera system with automatic aiming towards enemy weak points, adjusted iteratively via agent chat [11:36].
• 13:17 — NeoStack Agent's "Studio" tab displaying image-to-3D integrations (Tripo 2.5, Meshy 6, etc.).
• 15:09 — Running parallel tasks: building a scaled dungeon arena map from the imported 3D assets in one conversation while implementing player combo attack animations in another [15:39].
• 18:49 — Agent execution log showing NeoStack running Play-in-Editor (PIE) test runs autonomously to debug combat hit registration and damage triggers.
• 19:48 — Presenter manually opening ABP_Unarmed to disable a broken Control Rig node to fix an animation glitch.
• 20:13 — Adding camera impact shake and a dodge dash maneuver on Left Shift [21:13].
• 22:07 — Generating custom knight and monk character meshes rigged to the UE5 Mannequin in Blender using Claude Code and importing them into Unreal Engine [22:43].
• 22:51 — Final gameplay test showing the player navigating the custom arena, engaging enemy groups with sword combat, health bars, target locking, and dodging.

Claims & numbers

• The presenter notes Claude Opus 5.5 was released "today" (September 22, 2026, per the benchmark graphic).
• According to the shown Terminal-Bench 4.0 graphic: Claude Opus 5.5 scored 66.4%, GPT-6 Astra scored 57.5%, Claude Fable 5.1 scored 54.3%, Claude Opus 5 scored 52.3%, and GPT-5.6 Sol scored 31.4% (Anthropic, Sept 22, 2026).
• The presenter cites the NeoStack UE 5.8 AI Agent Benchmark (run July 31, 2026): NeoStack finished #1, completing 3 of 5 tasks (3x next best, Epic MCP at 1/5 and Aura at 1/5, others 0/5), with 145 total requests (fewest), 14 failed requests, and 36.4 minutes total runtime.
• The presenter states the entire core game prototype took approximately 20 minutes to assemble with AI prompting.
• The presenter notes NeoStack supports Unreal Engine 5.5, 5.6, 5.7, and 5.8 on Windows and macOS.

Notable quotes

• "Everything on your screen was made completely by the AI: the level, the systems, even the 3D models built inside of Blender—all of it." [00:11]
• "It was actually playing the game, I just was not recording at this moment as you can see... and fixing itself, which is a thing that—it blows my mind." [18:50]
• "This is the only thing that I've done manually, guys, okay? I swear." [20:07]

Assessment This is a genuine, hands-on sponsored demonstration and tutorial by an independent game development creator showing how to orchestrate Claude Opus 5.5, Claude Code, and the NeoStack Unreal Engine plugin. While several minutes of generation and compilation time are condensed with jump cuts, the video transparently shows raw terminal scripts, Blueprint graphs, iterative prompt corrections, and a manual fix for an animation control rig bug.

Described by gemini-3.8-flash on 2026-09-29 from the video's audio and frames.