NN666Chain

Gravity strategy for quick matches. Drop discs into an upright seven-column board and be the first to connect four in a row horizontally, vertically or diagonally. A typical game lasts a few minutes, and everything works fully offline.

PLAY YOUR WAY
- Against the computer: choose Beginner, Standard or Advanced. Beginner takes an open win and blocks direct threats. Standard looks four moves ahead and handles blocks and double threats. Advanced looks six moves ahead and scores open lines and central control. Each level can be beaten with careful play.
- Two players on one device: take turns on the same screen, and choose who moves first before each match.

HOW A DISC LANDS
Pick a column and the disc falls to the lowest empty cell. Tap a column to preview where the disc will land, then tap it again or wait a moment to drop the disc. Full columns are clearly marked and cannot be chosen.

THE MATCH SCREEN
See whose turn it is and which disc style belongs to each side. Pause, restart or resign at any time. In a casual game against the computer you may undo one full round, once per game. If you prefer to confirm every move with a second tap, turn off the drop delay in Preferences.

RESULTS AND REPLAY
When a line of four forms, the four winning discs are highlighted. The result screen shows the total number of turns and the decisive disc, and lets you step through the whole game move by move. You can rematch with the same settings, rematch with the first move swapped, or return to mode selection.

TACTIC PUZZLES
Thirty-six puzzles in three groups of twelve:
- Win in One: complete a line of four on this turn.
- Unique Defense: block the only safe column, then win within four of your turns.
- Double Threat: create two winning threats and win within two of your turns.
Every puzzle has a turn limit. Restart a puzzle to try again.

LEARN THE BASICS
A short interactive lesson shows how discs drop, the four winning directions, and how to block an opponent's threat.

STATISTICS AND SAVED GAMES
Track wins, losses and draws for each computer level, your fastest win, two-player results and puzzle completion. Unfinished games are saved on this device and can be continued later. A game pauses automatically when you leave the app.

PREFERENCES
Choose one of two disc styles, each with its own shape and texture, and pick the system, light or dark theme. You can also turn column hints, sound effects and the drop animation on or off. Settings can be reset at any time.

PRIVACY
Everything stays on your device. The game needs no account, does not use an internet connection, and does not share data with third parties. You can erase all local progress from Preferences.