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Building the Next Temtem or Coromon?

Games like Temtem, Coromon, Cassette Beasts, Nexomon, Monster Sanctuary, and Siralim have proven that the monster capture genre is thriving beyond Pokemon. Each of these games carved out its own identity with unique mechanics, art styles, and design philosophies.

But they all share one thing in common: years of engine development before they could start making their actual game.

OpenMon eliminates that bottleneck.

What These Studios Built from Scratch​

Temtem (Crema, Unity)​

Temtem is arguably the most ambitious independent monster capture game ever made. A fully online MMO with competitive battles, housing, and a living world.

What it took:

  • 30+ person development team
  • 5+ years of development
  • Custom battle system built on Unity
  • Custom networking layer for persistent online world
  • Custom breeding, evolution, and capture systems
  • $573K Kickstarter + ongoing development funding

Temtem is a tremendous achievement. It is also a cautionary tale about scope: the studio spent years building engine systems that are not unique to their game. The battle formula, type chart, capture mechanics, and monster data systems are genre-standard implementations.

Coromon (TRAGsoft, Custom C++)​

Coromon took the opposite approach -- a tiny team with a custom engine built from scratch in C++.

What it took:

  • 2-4 developers
  • 4 years of development
  • Entirely custom engine (no commercial engine)
  • Custom rendering, audio, input, and save systems on top of genre systems

The result is a polished, critically acclaimed game. But the custom engine is not reusable by other developers, and the C++ codebase requires deep expertise to maintain.

Cassette Beasts (Bytten Studio, Godot)​

Cassette Beasts chose Godot and built a monster capture game with a standout fusion mechanic. The small team leveraged Godot's flexibility to create something genuinely innovative.

What it took:

  • ~5 developers
  • 3 years of development
  • All monster capture systems built from scratch in GDScript/C#
  • Custom fusion system that generates combined sprites at runtime

Nexomon: Extinction (VEWO Interactive, Unity)​

Nexomon delivered a budget-friendly monster capture experience across all platforms using Unity.

What it took:

  • Small team
  • 2+ years of development
  • Custom battle and capture systems in Unity
  • Cross-platform deployment (PC, Switch, PS, Xbox, Mobile)

Monster Sanctuary (Moi Rai Games, Unity)​

Monster Sanctuary combined Metroidvania exploration with monster capture and turn-based battles -- started by a single developer.

What it took:

  • Started as 1-person project, grew to small team
  • 4 years of development (including Early Access)
  • Custom battle system blending monster capture with Metroidvania progression
  • Custom monster ability trees and equipment systems

The Common Thread​

Every studio spent 12-24 months building the same foundational systems:

  1. Monster data architecture (species, stats, IVs, EVs, natures)
  2. Battle engine (turn order, damage calculation, move effects, status conditions)
  3. Type effectiveness system
  4. Capture mechanics
  5. Evolution system
  6. Save/load serialization
  7. Overworld movement and encounters
  8. UI for battles, menus, storage, and Pokedex

These systems are table stakes for the genre. They are necessary but not differentiating. No player has ever said "I love this game because its damage formula implementation is elegant."

What Actually Makes These Games Special​

GameDifferentiator
TemtemMMO world, competitive focus, co-op battles
CoromonDifficulty modes, potential system (replaces IVs), puzzle-heavy world
Cassette BeastsFusion mechanic, open world, tape-based theming
NexomonHumor, accessibility, budget price point
Monster SanctuaryMetroidvania exploration, monster equipment, keeper battles
Siralim Ultimate1,200+ creatures, infinite dungeon, extreme depth
PokeMMOCommunity-driven MMO, nostalgia, competitive scene
AethermancerCard-based capture, deckbuilding integration

Every game on this list is memorable for what it does differently -- not for its implementation of standard battle mechanics.

The OpenMon Proposition​

OpenMon provides the 12-24 months of engine work these studios did, ready to use:

SystemOpenMon Status
Monster data architectureComplete with ScriptableObject databases
Battle engine (15+ modules)Complete with pluggable AI
Type effectivenessComplete with visual chart editor
Capture mechanicsComplete with configurable formulas
Evolution (30+ types)Complete
Save/load with versioningComplete
Grid-based overworldComplete
Encounter systemComplete
Event/scripting (CommandGraph)Complete
Quest systemComplete
UI (battle, menus, dex, shops)Complete
Online/MMO (20 services)Complete (Online tier)

Your job: Build the thing that makes your game special. The fusion mechanic. The Metroidvania exploration. The co-op mode. The story that makes players care.

Realistic Expectations​

OpenMon does not make game development easy. It makes it focused.

You still need to:

  • Design original monsters with unique art, stats, and movesets
  • Build your world with maps, NPCs, story, and events
  • Create your art -- sprites, tilesets, UI themes, animations
  • Compose or license music that fits your game's tone
  • Design your unique mechanics that set your game apart
  • Playtest and balance extensively
  • Market and launch your game

What you do NOT need to do is spend a year implementing damage formulas, debugging edge cases in multi-hit moves with abilities that prevent fainting, or building a save system that handles monster data serialization with backward compatibility.

Success Stories Are Coming​

The monster capture genre is in a golden age. Players are hungry for new games with fresh ideas. The studios that will succeed are the ones that ship faster and iterate on what makes their game unique.

OpenMon exists so the next Temtem, Coromon, or Cassette Beasts can focus on being different instead of rebuilding the same engine for the fifth time.

Get Started​