About NOVA
NOVA is a free sliding-number puzzle that runs entirely in your browser. There is no account, no install, no paywall and no timer. You slide a 4×4 grid one cell at a time, fuse a 2 and a 3 into a 5, and then double your way upward for as long as the board lets you.
Where it came from
The sliding-merge puzzle is a small, well-explored genre, and one of the better browser versions of it — the one that used to sit at threesjs.io — stopped loading. NOVA was built to fill that gap: something in the same shape that is free, fast, works on a phone, and is not going to quietly disappear.
It is not a copy of anything. The engine, artwork, sound and text are all original, and the design deliberately pulls away from the classic formula in a few places. If you are curious about the specifics, the comparison page lays them out.
What makes it different
- A different number ladder. Most games in this genre start 1 + 2 = 3. NOVA starts 2 + 3 = 5 and doubles from there, which changes the early board considerably.
- The Flux ★ wildcard. An original mechanic. Once you reach 40, a tile starts appearing that merges with anything — upgrading a stray 2 or 3 to a 5, or doubling anything larger. It creates a real decision: spend it now, or walk it to your big tile.
- Three undos per run. Enough to survive a misread swipe, not enough to brute-force the board.
How it is built
NOVA is a single page of plain JavaScript. No framework, no bundler, no third-party libraries, nothing to compile. That is a deliberate choice rather than a limitation: it means the whole game is a few tens of kilobytes, it starts instantly on a slow phone connection, and there is no dependency that can break it a year from now.
The sound is synthesised in the browser with the Web Audio API rather than downloaded as files, which is why there is no loading delay before the first merge makes a noise. Merge tones are pitched along a minor pentatonic scale so that chained merges never clash. Particle effects are drawn on a canvas that only animates while something is on screen.
The whole thing respects prefers-reduced-motion: if your system asks for
reduced motion, the animations and particles switch off and the game plays exactly the same.
Privacy and data
The game has no server and no database. Your best score is stored in your own browser and never leaves your device. Traffic is measured with Vercel Web Analytics, which is cookie-free and does not build a profile of you. The full detail is on the privacy page.
How the site is funded
NOVA is free and intended to stay that way. Hosting and the domain are paid for by advertising shown around the game. Ads are kept out of the play area — you will never get an interstitial between runs, a video you have to watch, or an ad you have to dismiss to keep playing.
Get in touch
Bug reports, ideas, and "your maths is wrong on the scoring page" emails are all welcome. The contact page has the address.