Hero Pets Simulator

Hero Pets Simulator is a collection and progression game where players defeat villains to grow their pets' power. It launched in March 2022 and has passed 1.5 million visits with an 84.2% positive rating.

The interesting engineering problem here is not the combat. It is the economy.

An economy spanning six orders of magnitude

Pets carry a rank that multiplies their value. The published tiers run from Bronze at 1x through Silver, Diamond at 10x, Lightning at 500x, Cosmic at 1,000x, Gode at 10,000x, Cyborg at 100,000x, and Hamburger at 1,000,000x.

A million-fold spread between the bottom and top of a progression ladder creates two problems at once. Numerically, values escalate fast enough that a careless implementation overflows or loses precision, and player-facing numbers have to stay readable rather than turning into unformatted scientific notation.

Design-wise, the gap between tiers has to feel achievable at every stage. A player holding a 1x Bronze pet needs the 10x tier to feel like a reachable next step, while a player at 100,000x still needs something to pursue. That is a pacing problem that has to be tuned against real progression data, not guessed at.

Gated progression and boss checks

Zones and maps unlock by defeating bosses. Gating is what stops a collection game from collapsing into an undifferentiated grind: it gives progression discrete milestones rather than a single continuous number climbing forever.

Every gate check is a server-side authority question. If the client decides whether a player has defeated a boss, the gate is decorative. Unlock state lives in the player's persisted data and is validated server-side on every zone transition.

Storing an inventory that only grows

Collection games have a data problem that combat games do not: the save grows without bound. Every pet a player acquires is another entry, and a dedicated player accumulates thousands. Roblox DataStores impose a size limit per key, and a naive implementation hits it eventually.

Storing each pet as a full object with every attribute spelled out wastes the budget fast. The economical approach stores references rather than copies: the pet's type is an identifier into a static definition table, and only the genuinely per-instance state, rank and accumulated power, is persisted. The definition table lives in code, where it costs nothing per player.

Serialisation matters at this scale too. A save that is compact enough to write quickly is also a save that is less likely to fail partway through, and DataStore write failures are the mechanism by which collection games lose player progress.

Drop rates and the appearance of fairness

A rank ladder reaching 1,000,000x only works if the top of it is genuinely rare. That rarity has to be enforced server-side: any roll that determines what a player receives is a decision the client must never make, or the rarest tier stops being rare within a day of the first exploit.

Perceived fairness is a separate problem from actual fairness. True independent probability produces long unlucky streaks that players read as a broken or rigged system. Tracking attempts since a player's last rare drop, and biasing accordingly, keeps the distribution close to its advertised rate while removing the streaks that drive players away.

Currency separation

The game runs parallel currencies, with coins and diamonds dropped by visually distinct villain types. Separating currencies by source is a deliberate economic tool: it lets the soft currency inflate with playtime while a scarcer currency holds its value, which is what keeps the progression ladder meaningful late.

Getting that separation right at design time matters, because currencies are extremely difficult to rebalance once players hold large stockpiles. We cover the underlying patterns in our monetisation guide and our game loop design guide.

Where the project stands

The game was last updated in January 2026 and is no longer in active development. Its lifetime figures, 1,573,132 visits and an 84.2% positive rating, are public on the Roblox game page. We include it here because the economy architecture is the transferable part, and that work is directly applicable to any collection or progression game facing the same tuning problem.