Skywave

Skywave is a daily puzzle from DEXM Labs, a small UK site of free browser games and simulators. It was built by Arthur, who lives in Lincolnshire, came to radio through planes and a software-defined radio, and made the game while studying for an amateur radio Foundation licence. It plays in the browser with no account, no cookies and no ads.

Each day's round is worked out from the UTC date, so everyone gets the same one. A briefing shows the solar flux, the K index, any flare watch or sporadic E, your home location and the ten stations to work, with the hours each one is listening. Then you go on air: choose one of eleven bands from 160m to 6m, FT8, CW or SSB, a power from 5 to 400 W and an antenna, aim a Yagi if you use one, and press Call. Every call costs ten minutes of game time whether it works or not, and the clock only moves forward, so waiting for a band to open is part of the plan.

A contact scores by distance, multiplied by the station's rarity, the mode and the power: low power and SSB pay more, and a grey-line contact adds a bonus. When a call fails, a hop table shows what stopped the signal, such as a frequency above the maximum usable frequency or too much D-layer absorption. Hints for the MUF, the D-layer loss or a six-hour band scope cost points you earn by finishing rounds, not your score.

The propagation model is simplified on purpose and the stations are fictional, so it is a game rather than a forecast. It suits radio amateurs and listeners who want a daily workout in reading conditions, and curious players who want to learn why some radio paths open at night and others by day. A practice mode lets you set your own solar flux, K index and date and play as often as you like without touching your streak.