Compound Interest

Build the Periodic Table
Compound Interest is a chemistry-themed incremental game about turning Hydrogen into an increasingly complex production engine.
Generate Energy and Matter, collect elements, and work your way across all 118 spaces of the periodic table. Completing periods, groups, and blocks grants bonuses and opens new paths through the game.
Find Your Own Fusion Paths
Fusion follows one rule: atomic numbers add together. Two Hydrogen make Helium. Three Lithium make Fluorine. Any combination that reaches a valid element can work, giving you different ways to use what you have and push further up the table.
Build with Compounds
Craft 45 compounds based on real chemical formulas, then equip them to shape your production. Compounds share tags such as Oxide, Organic, Crystal, and Fuel. Combining related tags creates synergies, while certain loadouts can trigger Combustion, Crystallization, Corrosion, and Explosions.
Radioactive elements decay into other elements and release Energy along the way. Research unlocks automation, isotope variants, stabilization, and lasting upgrades. When progress slows, trigger a Big Bang, earn Cosmic Dust, and begin again with permanent bonuses.
The game continues while closed, with up to 24 hours of offline progress.
Features
All 118 Elements — Collect and fill the complete periodic table

Open-Ended Fusion — Combine atomic numbers to discover heavier elements

45 Compounds — Craft compounds with real formulas and gameplay effects

Compound Loadouts — Combine tags to create synergies and trigger reactions

Radioactive Decay — Unstable elements transform and release Energy

Research and Automation — Unlock auto-clicking, fusion, synthesis, and compound crafting

Isotope Variants — Choose between light, standard, and heavy forms

Big Bang Prestige — Reset your run in exchange for permanent upgrades

Discovery Journal — Record compounds and learn related chemistry facts

Offline Progress — Accumulate resources for up to 24 hours while away