The first and only production-grade framework for building monster-catching RPGs.
Available for Unity 6 and Unreal Engine 5.
Website • Documentation • Discord • X / Twitter
OpenMon (also known as MCE — Monster Capture Engine) is the complete game framework for building Pokemon-like, Temtem-like, Coromon-like, and entirely original monster-catching RPGs. It provides everything a developer needs to ship a commercial monster capture game — battle systems, monster databases, grid-based worlds, visual event scripting, save systems, online multiplayer, and more — out of the box.
Whether you're an indie developer building the next Cassette Beasts, a small studio prototyping a creature collector, or a hobbyist converting a Pokemon Essentials project to a modern engine, OpenMon gives you a 12-18 month head start.
OpenMon is not a tutorial or a prototype. It is a production engine with 90,000+ lines of code, 2,344+ automated tests, and 668 fully-configured monsters ready to use or replace with your own original creatures.
| Challenge | Without OpenMon | With OpenMon |
|---|---|---|
| Battle system | 6-12 months of engineering | Ready on day one |
| 668+ moves with effects | Build each from scratch | All included, data-driven |
| Monster stats, natures, IVs, EVs | Implement Gen V+ formulas | Battle-tested, verified |
| Type effectiveness (18x18) | Manual implementation | Complete chart included |
| Grid-based overworld | Custom tile engine | Built on Unity Tilemaps / Paper2D |
| Save/load system | JSON serialization from scratch | Versioned, migration-ready |
| Pokemon Essentials import | Impossible | One-click import pipeline |
| Multiplayer/MMO | 6-12 months for networking | 20 online services included |
| Total time saved | 12-18 months | Start making YOUR game |
The most comprehensive turn-based battle system available for any game engine.
- 668+ moves — every move is data-driven with power, accuracy, PP, type, category, priority, and 29 parameterized effect types
- 18-type effectiveness chart — full Gen VI+ chart with Fairy type, dual-type support, and immunity handling
- 229 abilities — Intimidate, Levitate, Huge Power, Adaptability, and 225 more with real game logic
- 74 volatile statuses — Confusion, Protect, Taunt, Leech Seed, Encore, and 69 more
- 17 side statuses — Stealth Rock, Spikes, Toxic Spikes, Reflect, Light Screen, Tailwind, and more
- 4 terrain types — Electric, Grassy, Misty, Psychic with damage/status modifiers
- 9 weather types — Sun, Rain, Sandstorm, Hail, Snow, Fog, Harsh Sun, Heavy Rain, Strong Winds
- 4 global statuses — Trick Room, Gravity, Magic Room, Wonder Room
- 27 held item effects — Life Orb, Choice Band, Focus Sash, Leftovers, berries, type-boost items
- 4 AI strategies — Random, Effective, Smart (multi-factor scoring), ML-ready neural network interface
- GAS integration (UE5) — Gameplay Ability System for moves, stats, and networking
- Gen V+ damage formula — fidelity-checked against the original game formulas
- Capture system — full shake probability, critical capture, ball bonuses, status bonuses
- 668 fully-configured monsters across 8 generations with stats, types, abilities, and evolution chains
- 34 evolution types — Level, Item, Trade, Friendship, Time, Location, Weather, Stats, Gender, and 25 more
- Breeding system — egg groups, IV/nature/move inheritance, Everstone, Destiny Knot
- Forms and Mega Evolution — form transitions, battle forms, Mega stones
- PC Storage — 14x30 box system with roster transfers
- Contest conditions, ribbons, virus (Pokerus equivalent), origin data, fusion support
- Tile-based movement — walk, run, bike, surf, ice sliding, ledge jumping, waterfall traversal
- 10 tile types — Walkable, Blocked, Water, Bridge, BridgeEntrance, Slippery, Ledge, Waterfall, and more
- A pathfinding* for NPCs
- Monster followers — party monster follows player with speed matching and dynamic sprite swapping
- Encounter system — 11 encounter types (grass, water, cave, fishing, headbutt, etc.) with progressive step formula
- Day/night cycle and weather system
- Cross-map transitions with grace system
Node-based visual scripting for creating NPC events, dialogs, shops, quests, and cutscenes — no code required.
- 34 node types — Dialog, Branch, Battle, Shop, Quest, Variable, Movement, Cutscene, Weather, and more
- 14 specialized nodes — Badge, Dex, Breeding, Trade, Storage, Nickname, MoveTutor, Cooking, and more
- Connect nodes in the editor, configure in the Inspector, done.
Build a PokeMMO-style MMORPG with 20 ready-to-deploy online services:
- Authentication — Email, device, Discord/Google/Apple SSO
- PvP Battles — ELO-based matchmaking, server-authoritative battles, spectating
- Economy — Multi-currency wallet, Global Trade Link (auction house), server-validated shops
- Social — 8-channel chat, guilds with roles, friends with presence, P2P trading
- World Sync — AOI-filtered player sync, interpolated network entities, NPC engagement locking
- Housing — Player housing with furniture grid placement
- LiveOps — Events, leaderboards, achievements
- Anti-Cheat — Speed hack detection, rate limiting, inventory validation, audit logging
- Cloud Save — Upload/download with conflict resolution, auto-rotating backups
Supports Nakama and Epic Online Services (EOS) backends.
One-click import of Pokemon Essentials v20, v21, and v21.1 projects:
- PBS text file parser (pokemon.txt, moves.txt, abilities.txt, items.txt, types.txt)
- Ruby Marshal RXDATA parser (maps, tilesets, events)
- Automatic conversion: species → MonsterEntry, moves → MoveData, maps → TileMaps
- Event classification: NPC, Warp, Door, Sign, ItemBall, Autorun
- Sprite and audio import with slicing
- 15-phase import pipeline with progress tracking
- Keep your maps, events, and game data — swap in original assets — publish commercially
Generate monster sprites, overworld characters, and tilesets directly from the editor using:
- PixelLab — Pixel art characters, tilesets, isometric tiles
- Nano Banana 2 — Monster sprite generation
- OpenAI / Stable Diffusion — General art generation
| Platform | Unity 6 | Unreal Engine 5 |
|---|---|---|
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| Android | Yes | Yes |
| iOS | Yes | Yes |
| WebGL | Yes | — |
| Nintendo Switch | Via Unity | Via UE5 |
| PlayStation | Via Unity | Via UE5 |
| Xbox | Via Unity | Via UE5 |
Pricing will be announced soon. Join the waitlist at openmon.io to get early access pricing.
| Feature | OpenMon | Pokemon Essentials |
|---|---|---|
| Engine | Unity 6 / Unreal Engine 5 | RPG Maker XP (Ruby) |
| Commercial use | Yes, fully licensed | Legal grey area |
| 3D support | Yes (URP/UE5) | No (2D only) |
| Multiplayer | 20 online services | None |
| Platforms | PC, Mobile, Console, Web | Windows only |
| Performance | Native C#/C++ | Ruby interpreter |
| Import PE projects | Yes, one-click | N/A |
| Active development | Yes (2026) | Community-maintained |
Building a monster-catching RPG from scratch typically requires:
- Battle system: 3-6 months
- Monster data model: 1-2 months
- Grid movement: 1-2 months
- Save system: 2-4 weeks
- UI (menus, battle HUD, dex): 2-3 months
- Online multiplayer: 6-12 months
- Total: 12-24 months, $50,000-$150,000
OpenMon ships all of this ready to use. Focus on what makes YOUR game unique.
| OpenMon | RPG Maker | GameMaker | Godot | Custom Unity | Custom UE5 | |
|---|---|---|---|---|---|---|
| Monster battle system | Included | Plugin | Manual | Manual | Manual | Manual |
| 668+ moves | Included | Manual | Manual | Manual | Manual | Manual |
| Type chart (18x18) | Included | Manual | Manual | Manual | Manual | Manual |
| PE import | Yes | No | No | No | No | No |
| Multiplayer | 20 services | No | Basic | Basic | Manual | Manual |
| Targeting | Monster RPGs | General RPGs | General | General | General | General |
| Price | See website | $80 | $100 | Free | Engine free | Engine free |
Yes. OpenMon is specifically built for monster-catching RPGs in the style of Pokemon, Temtem, Coromon, and Cassette Beasts. It includes a complete battle system, 668 monsters, evolution, breeding, grid-based worlds, and everything else you need. Replace the included monsters with your own original designs and you have a commercially publishable game.
Pokemon Essentials is a free fan-made framework for RPG Maker XP. OpenMon is a commercial framework for Unity and Unreal Engine. The key differences: OpenMon supports commercial publishing, multiplayer, cross-platform deployment (PC/Mobile/Console/Web), 3D graphics, and modern development tools. OpenMon can also import your existing PE project and convert it automatically.
Absolutely. OpenMon is commercially licensed. You own your game, your assets, your code. Publish on Steam, Epic Games Store, Nintendo eShop, PlayStation Store, App Store, Google Play — no restrictions. The only requirement: your art, story, and monster designs must be original (not copies of existing IP).
Yes. OpenMon v3.0 is a native C++ UE5 plugin with 90,000+ lines of code. It uses Paper2D for sprite rendering, PaperZD for 2D animation, GAS (Gameplay Ability System) for the battle system, and CommonUI for menus. Available on Fab by Epic Games.
OpenMon's Online module provides all the systems needed to build a PokeMMO-style game: PvP battles with ELO matchmaking, a Global Trade Link (auction house), guilds, 8-channel chat, player housing, and 20 online services total. It uses Nakama or Epic Online Services as the backend.
Yes. The Monster Creator wizard lets you define species from scratch: name, types, base stats, abilities, evolution chains, egg groups, sprites. Design 10 monsters or 1,000 — the system is data-driven and scales to any roster size. The AI Art Studio can generate pixel art sprites for your designs.
Yes. OpenMon includes a one-click importer for Pokemon Essentials v20, v21, and v21.1 projects. It reads PBS text files and RXDATA binary files, converting species, moves, items, maps, tilesets, events, and encounters into OpenMon's format. Your maps and game logic transfer automatically.
Yes. The Online module provides 20 services: authentication, PvP matchmaking, server-authoritative battles, trading, guilds, housing, economy (wallet + auction house), cloud saves, leaderboards, achievements, events, anti-cheat, and more. It supports both Nakama and Epic Online Services backends.
Every one of these studios built their engine systems from scratch, spending 12-18 months before writing a single line of their actual game. OpenMon provides that same foundation — battles, monsters, worlds, saves, multiplayer — ready to use. You focus on what makes YOUR game different: art style, story, unique mechanics.
OpenMon is a commercial product, but the documentation, demo project, and API reference are all free at openmon.io. Pricing will be announced soon -- join the waitlist for early access.
Pokemon Champions is a fan game. OpenMon is a development framework — a tool for CREATING monster-catching games, not a game itself. You use OpenMon to build your own original game that you own and can sell commercially.
OpenMon is designed for traditional turn-based RPGs with grid-based overworlds. A Pokemon GO-style AR game requires GPS, camera, and real-world mapping — different technology. However, OpenMon's monster data model, battle system, and capture mechanics could serve as the combat backend for a hybrid approach.
The documentation at openmon.io/docs is available in English, Spanish, Japanese, Russian, and Chinese (Simplified).
The monster-catching genre is exploding. Developers, communities, and players have proven time and again that the demand for creature-catching games is massive and growing. OpenMon exists because this revolution needs a production-grade engine.
The crowdfunding numbers speak for themselves:
- Elestrals Awakened raised $1.4M on Kickstarter in 2025, making it the most-funded monster-catching game of the year. That is $1.4 million in demand for a genre most publishers still ignore.
- Monsterpatch, a cozy monster collector, hit 1,500% of its funding goal. Players are starving for wholesome creature-catching games.
- Tomo: Endless Blue brings open-world voxel exploration to the monster genre and found its audience on Kickstarter before writing a single line of marketing copy.
These are not outliers. They are proof that the monster-catching market is large, passionate, and willing to pay for quality.
The Pokemon fan game community is one of the most prolific in all of gaming. These projects have millions of downloads and years of development behind them:
- Pokemon Reborn -- one of the most ambitious fan games ever made, with millions of downloads, 18 gyms, a dark storyline, and field effects that changed how the community thinks about battle design
- Pokemon Insurgence -- mega evolutions, delta species, a complete Pokedex, millions of downloads
- Pokemon Rejuvenation -- a spiritual successor to Reborn with its own massive following
- Pokemon Unbound -- GBA-style with modern QoL features, widely considered one of the best ROM hacks ever made
- Pokemon Infinite Fusion -- generates 200,000+ monthly searches and lets players fuse any two Pokemon together, with community-contributed sprites numbering in the hundreds of thousands
- Pokemon Uranium -- nine years of development, a full original region with 150+ original fakemon, then DMCA'd by Nintendo despite never using a single line of Game Freak's code
- Pokemon Xenoverse -- built by an Italian team, complete with DLCs, fully voice-acted, one of the most polished fan games in existence
- Pokemon Unbreakable Ties -- set in the tropical Akebia region with Gen 9 support, pushing the boundaries of what Pokemon Essentials can do
- Pokemon SoulStones 2: Time Wardens -- widely praised as setting a new bar for fan games in 2026
- Pokemon Realidea System -- another standout demonstrating the genre's creative depth
Every single one of these developers faces the same problem: they cannot sell their games commercially. Years of work, millions of players, zero revenue. They are locked into Pokemon Essentials on RPG Maker XP, using copyrighted assets, with no path to the market.
OpenMon solves this. Import your Pokemon Essentials project, replace the IP with your own original creatures, and publish on Steam. Your maps, your mechanics, your events, your stats -- they all transfer. The only thing that changes is the IP. The game you built becomes the game you own.
The commercial market for monster-catching games is worth billions:
- Temtem (Crema) -- $500M+ franchise value, proved that a non-Pokemon monster catcher can succeed on PC and console
- Palworld (Pocketpair) -- $400M+ revenue in 2024 alone, the fastest-selling game on Steam with creature-catching mechanics at its core
- Coromon (TRAGsoft) -- indie success on Steam with retro pixel art, demonstrating that small teams can compete
- Cassette Beasts (Bytten Studio) -- critically acclaimed, fusion-based monster system, strong sales on PC and Switch
- Nexomon (VEWO Interactive) -- successful on mobile, PC, and console with two entries in the franchise
- Monster Sanctuary (Moi Rai Games) -- metroidvania hybrid that proved the genre can be mixed with other gameplay styles
- Siralim Ultimate -- 1,200+ monsters, deep mechanics, a devoted player base
- Aethermancer -- upcoming title generating significant community interest
Every one of these studios built their engine systems from scratch, spending 12-18 months on battle systems, stat formulas, type charts, and encounter logic before they could start making their actual game. OpenMon provides that same foundation ready to use -- so you can focus on what makes YOUR game unique: your art style, your story, your world, your mechanics.
The monster-catching revolution is here. The tools to join it are ready. Get started with OpenMon.
| Spec | Unity 6 | Unreal Engine 5 |
|---|---|---|
| Language | C# | C++ |
| Lines of code | 161,000+ | 90,000+ |
| Automated tests | 2,114+ | 2,344+ |
| Monster species | 668 | 668 |
| Moves | 656 | 656 |
| Abilities | 202 | 229 |
| Items | 1,989 | 109 (demo) |
| Render pipeline | URP | Paper2D + PaperZD |
| DI framework | Zenject | UE5 Subsystems |
| Battle system | Custom modules | GAS + Custom modules |
| Online backend | Nakama | Nakama + EOS |
| Scripting | CommandGraph (visual) | CommandGraph (visual) |
- Website: openmon.io
- Documentation: openmon.io/docs
- Discord: discord.gg/zszqu7sPuY
- X / Twitter: @openmon_io
- GitHub: OPENMON-IO
OpenMon is commercially licensed software. See openmon.io/docs/license for details.
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