In the lightless bottom of a dungeon, you are the mastermind who hatches abominations, raises them, and sends them up to the surface world.

Abyssal Breeder's Journal is a dark monster-breeding sim told in text and pixel art. Hatch a larva, spend training cards from a drawn hand to grow its stats, survive TRPG-style event checks, and watch it warp through five tiers of mutation. When its lifespan runs out, you choose: deploy it to fight on the surface, or station it as a guardian defending your domain. Either way, you never see that individual again — but the Factors and Traits it leaves behind carry into the next generation.

Two things sit at the center of every run: your hand of training cards, and two meters pulling against each other — Madness and Morale. Push Madness high enough and mutation routes open up, but too far and your creature starts refusing its turn, or an experiment backfires on you. Keep Morale up and every training session gets a bonus instead. Every card you play is a small bet between power and control.

The real hook is breeding across generations. A creature's final stats distill into Factors when it ships out; whatever Traits it was born with or grew into stay separate. These are two fully independent inheritance tracks — hatching the next larva, you choose up to three Factors and any Traits to carry forward, on top of a brand-new random trait for the newborn. It's less "hope for a good roll" and more "design the bloodline you're after, one generation at a time." An Ancestral Boon also compounds quietly in the background: a permanent bump to starting stats that grows with every individual you ship or station, so nothing you raise is wasted, even the ones that don't make the cut.

There's a second game running above the dungeon. Send creatures to raid, sabotage, or burn cities to expand your territory. Station guardians to hold real-time sieges when the surface strikes back. Take prisoners and decide what becomes of them. Spend souls at the black market. Cross-breed multiple bloodlines to unlock mythic hybrids no bestiary has ever recorded. What you do on the surface changes what comes for you underground — and vice versa.

There's no stamina system. A generation runs about 10–15 minutes, and nothing stops you from starting another the moment it ends.

Key features

• TRPG-style training cards — draw a hand each turn; the deck skews bloodier as Madness climbs. A persistent Grimoire lets you build your own deck across generations, not just this one.

• Madness vs. Morale — a real tradeoff, not a meter you can ignore. Push too far into Madness and creatures start refusing orders.

• Factors and Traits inherit on two fully separate tracks — chase a stat build and a trait build independently, generation after generation, plus a compounding Ancestral Boon.

• Four-phase deployment battles with real crits and fumbles, procedurally generated Epithets for standout individuals, and species-specific logs of what happens after you let a creature go.

• A second layer on the surface — territory conquest, real-time domain defense, a black market, a prison, and forbidden cross-breeding for mythic new species.

• No stamina, no timers. Run one generation or twenty in a sitting.

• Japanese, English, Simplified Chinese, and Traditional Chinese, switchable anytime from the settings menu.

Is this for you?

• You like monster-breeding or creature-collecting games, and want the version where you actually have to let go of what you raise.

• You're into roguelite or hack-and-slash loops where the grind compounds into something, rather than resetting.

• Dark fantasy and TRPG dice appeal to you more than a friendly mascot would.

• You want a session you can start and finish in fifteen minutes without losing progress, and repeat as many times as you like.