// tools
AI RPG Tools
Two problems define AI roleplay: choosing the right platform to begin with, and keeping your campaign coherent once you're running. These tools address both — one at the start of the journey, one deep inside it. No accounts. No data sent anywhere. Everything runs in your browser.
Built by Rukka — four decades across tabletop RPGs, CRPGs, MMOs, and AI-driven roleplay systems — these tools come out of the same thinking behind the Arcanum Originals: that a long AI campaign isn't luck, it's architecture. The right structure makes the difference between a story that holds together and one that quietly falls apart by session four.
Campaign Memory Tool
Around turn 50, AI campaigns hit a wall: the model starts losing coherence as older messages scroll out of context. This is the turn-50 amnesia problem — the most common failure in long AI roleplay — and this tool gives you a structured place to fight it. Log everything that matters: characters, plot threads, locations, relationships, inventory, world facts, and a last-scene anchor.
When the context gets heavy, hit Generate Compression Prompt. The tool outputs a briefing you paste into ChatGPT, Claude, or Gemini. The AI reads your full campaign state and returns a compact memory block — under 500 words — that you paste at the start of every new session to restore full context. Your data saves to a .arcanum file on your device; nothing is sent to any server.
AI RPG Prompt Builder
The gap between "I want to run an RPG in ChatGPT" and a session that actually holds together is almost always the system prompt. This tool builds one in under a minute: select your model, genre, tone, focus, and campaign length, and it assembles a structured, copy-paste-ready system prompt — no AI called, no account needed, runs entirely in your browser.
Drop the result into ChatGPT as Custom GPT instructions, a Claude Project's custom instructions, or a Gemini Gem. The prompt establishes genre, tone, agency rules, and memory continuity from turn one. Use the Long Campaign option to append save-state and compression instructions that pair directly with the Campaign Memory Tool.
Open tool →AI Character Card Generator
A blank character field is where most people stall. This generator rolls a complete, coherent character in a click: pick a setting, archetype, and tone — or leave them on Any — and it assembles a paste-ready card with personality, scenario, an opening message, and example dialogue, formatted for Janitor AI, SillyTavern, and any platform that reads the card format.
It's a generator, not a chatbot — no AI is called and nothing leaves your browser. Each roll combines an archetype's core voice with independently sampled quirks, speech, flaws, and scenarios, so Re-roll keeps giving you genuinely different characters. Copy or download the result, then sharpen it using the character card writing guide.
Open tool →Context Budget Calculator
Every AI RPG dev fights the same problem: a context window is finite, and most people eyeball how much of it their system prompt, world file, and memory block have already eaten. Pick a model — Claude, ChatGPT, Gemini, Grok, or DeepSeek — paste in your fixed content, and this tool shows exactly how much room is left for actual play.
It also estimates roughly what turn you'll hit the wall, based on how many tokens an average turn costs you. No AI is called and nothing leaves your browser — same rule as every tool here. Pairs directly with the turn-50 amnesia problem this whole memory cluster exists to solve.
Open tool →Platform Comparison Matrix
26 reviewed AI roleplay platforms — Friends & Fables, RoleForge, Janitor AI, and 23 more — in a single sortable table. The columns that matter most: rating, pricing tier, which AI models run under the hood, and how each platform handles memory across sessions.
Filter by free or freemium. Sort by rating or platform name. Click through to the full review for any entry. The Memory column alone tells you which platforms can sustain a six-month campaign and which ones degrade by session four — that distinction is harder to find anywhere else.
Open tool →Why These Tools Exist Separately from the Games
The AI RPG Prompt Builder is for the question before the first turn: how do I give the AI the instructions it needs to actually run a game? A well-structured system prompt defines genre, tone, agency rules, and memory continuity before the player types a single word — it is the difference between a session that holds together and one that quietly improvises its way off the rails by turn ten.
The comparison matrix is for the question before the campaign starts: which platform is actually worth your time? It pulls every reviewed client into one place so you can make that call without opening ten tabs — and points directly into the full write-up when you need the reasoning behind a rating.
The Campaign Memory Tool is for the question that arrives around session four: why does the AI keep losing the thread? Context windows fill. Models drift. Characters forget what happened ten scenes ago. The tool gives you a structured place to fight that — state logging, a compression prompt, a .arcanum file that saves to your device.
The Arcanum Originals — Aevum, Eirathis, The Chronicler, Star Freighter Drift — solve the memory problem from the inside, with compression and state management built into the system prompt itself. If you download one of those games, you don't need the Campaign Memory Tool. But for homebrew campaigns running in any model, on any platform — these tools bring the same structural discipline without requiring you to change how you play.
If you haven't read why AI campaigns fall apart at turn 50, that article is the technical foundation behind both the memory tool and the Originals. Understanding the context window problem — and the specific fixes that work — makes everything here more effective.