How to play
- Choose a column to drop your piece into the lowest open space.
- Look for horizontal, vertical, and diagonal ways to connect four.
- Block immediate threats while creating two possible winning moves of your own.
What this game practices
A compact introduction to look-ahead and competing constraints. The small rule set makes decisions visible, although computer difficulty influences how much planning is required.
How we checked it
Open-source HTML5 game reviewed in the local coolmath build for startup, primary controls, restart flow, narrow-screen fit, console errors, failed requests, and third-party network activity. Upstream telemetry is disabled in this self-hosted copy.
Open-source license and attribution
This self-hosted game is adapted from Web Games by mashukui and distributed under the MIT License. coolmath disabled upstream telemetry and records its local changes in the open-source notices.
Reviewed by coolmath Editorial Team · Updated 2026-10-09