Isotope - Chain Reactor

Place one orb. Watch the whole board light up. Strategic chain reactions, 7 AI opponents, and an endless mode that punishes hesitation. Free.

Drop an orb, watch the board explode. Isotope is a snappy, free-to-play take on the classic chain-reaction strategy game — turn-based, beautifully drawn, and built to be played in two-minute bursts on the bus or two-hour sessions on the couch.

The rules are simple. The strategy is not.

Tap any empty cell, or stack on a cell you already own, to drop one orb. When a cell hits its critical mass — 2 for corners, 3 for edges, 4 for the middle — it FISSIONS. The orbs scatter to every neighbour, instantly capturing whatever was there. Daisy-chain enough explosions and the entire board can flip in a single turn.

Last colour standing wins.

— GAME MODES —

DUEL — One-on-one against seven distinct AI opponents, each with a different playstyle. Start gentle with Sparky on a 4×4 board, work your way up to Nova on the 7×9 grid. Beat each AI with 1, 2, AND 3 cycling colours to fully master it.

WEEKLY CHALLENGE — A handcrafted puzzle every week. Solve it in the exact number of moves to claim the coin reward — Beginner (50 coins) up to Master tier (250 coins).

ENDLESS — Random board, random difficulty, every wave. How far can you push the cascade before the AI corners you?

TRAINER — Both sides played by you, on any board size up to the 9×7 giant. No score, no AI — just pure positional study.

— FEATURES —

• Six visually distinct elements — Uranium, Thorium, Radium, Radon, Polonium, Plutonium — purely cosmetic, mechanically identical • 1-, 2-, or 3-colour cycling play at higher difficulties for an extra strategic layer • Boosters: Hint (50 coins), Undo (75 coins), Skip an AI turn (100 coins) • Daily login bonus + weekly challenge rewards + watch-to-earn coins • Looping ambient soundtrack and a satisfying blast SFX for every cascade • Haptic feedback that scales with cascade depth • Music, Sound FX, Haptics, and Volume all controllable in Settings

— PRIVACY-FIRST —

• 100% playable offline • No account required — no sign-up, no login, no email • Save data is stored on your device only • Personalised ads only with your explicit App Tracking Transparency consent

— FREE-TO-PLAY DETAILS —

Isotope is free to download and play. Optional rewarded ads grant in-game coins; an optional one-time "Remove Ads" purchase disables them entirely. Coins are an in-game currency only — they have no real-world value and can't be exchanged for cash.

Built by Genesis Solutions.