Shadow Chase
Shade never falls straight under the thing that makes it: it lands on the side away from the sun, as far out as the height divided by the tangent of the sun's angle, and it moves all day. Shadow Chase is a game about exactly that. Put umbrellas, sails and an awning in a garden, then watch the real sun for that place and date cross the sky and see who stays cool.
Shadow Chase
Place shade before the day starts, then watch the real sun cross a real garden. Every guest-hour in the shade scores 20; every coin you spend comes off.
Shadow Chase
Drag to move, two fingers or the turn buttons to turn a sail. A sail's corners tie to the back wall or a tree for free; anywhere else needs a post.
Shade falls on the side away from the sun. At 1 pm in London on 21 June the sun is 62° up, so an umbrella rim 2.0 m (6 ft 7 in) high throws its shade about 3 ft 6 in (1.1 m) away from it: stand the umbrella a step sunward of the seat. The patio umbrella size calculator does this for your own table.
The shade swings round as the sun moves: in London on 21 June it goes from the south-south-east at noon to the south-south-west by 2 pm, and the shadow slides from one side of the table to the other. Moving the umbrella once at midday keeps the whole table covered. How to choose a patio umbrella covers tilting and cantilever umbrellas, which follow the sun for you.
In Phoenix on 15 July the noon sun is 78° up and shade falls almost straight down, but by 4 pm the sun is 43° up in the west and an umbrella rim 2.0 m (6 ft 7 in) high puts its shade 2.1 m (7 ft) to the east. Shade that is right at noon is wrong by mid-afternoon: put it where the shadow will be, not where the sun is. More in shade for hot climates.
In the morning the sun is in the east and an umbrella's shade lies to the west of it; by 4 pm the sun is in the west-south-west and the shade has crossed to the east. One move at midday does the work of a second umbrella. How the sun moves across your garden explains the swing.
Facing north, the house stands between the patio and the midday sun: at 1 pm on 10 July in London the sun is 61° up, and a house 20 ft (6 m) high throws its shade about 11 ft (3.4 m) into the garden. That covers the patio but not the far end, which is where the shade had to go. The which way does my garden face tool works out the sun on your own garden.
With the sun high and in front of a south wall at midday (70° up at 1 pm in Chicago on 15 July), an awning's shade sits right under it, along the wall where the table is. Size one for your wall with the awning size calculator; types of awnings and what they cost and retractable or fixed cover the buying.
At 7 pm in London on 21 June the sun is 19° up in the west-north-west. That low sun slides straight under an awning, and anything 6 ft 11 in (2.1 m) up throws its shade about 20 ft (6.3 m) back toward the house. A sail out toward the sun, at the right height, puts that long shadow on the table. How to install a shade sail and sail, awning or pergola go further.
South of the equator the midday sun is in the north: in Sydney on 25 December it stands 80° up due north at 12:55 pm, so shade falls to the south, toward a house whose garden faces north. Everything in the other levels works the same way, mirrored. How the sun moves across your garden has the why.
A tree is free shade and a free corner for a sail, but its shadow walks round it through the day, to the west in the morning and the east in the afternoon, and lengthens as the sun drops. Shade sail, awning or pergola compares the built options, and a louvered pergola turns its roof to follow the sun.
In London on 21 December the noon sun is only 15° up, so a 6 ft (1.8 m) fence casts a shadow about 22 ft (6.7 m) long. In winter the sunny seats are the ones far from anything tall, and the shade you put up for summer should let that low sun in: the best shade for a south-facing garden shows how.
How to play
- Plan. Each level is a garden seen from above with the house along the top, a place, a date and guests who arrive and leave at set times. Pick a piece of shade, tap the garden to place it, drag it to move it. The shadows you see while planning are for the middle of the guests' time.
- Play. Start the day and the sun rises, crosses the sky and sets in about 75 seconds (faster with the speed button). A guest in the sun glows amber and their comfort ring runs down.
- Midday. When the sun crosses the meridian the game stops once: you may move each umbrella one time, as you would at a real lunch.
- Score. Every guest-hour spent where the guest wants to be earns 20 points, and every coin you spent comes off. Three marks on each level give one, two or three stars. Your best is kept in this browser.
On a keyboard: Tab to a piece of shade and press Enter to put it in the middle of the garden, then use the arrow keys to move it (Shift for bigger steps), R and Shift+R to turn a sail, H to raise or lower its posts, N to pick the next piece and Delete to remove it. On a phone, two fingers turn a sail.
How the shadows are worked out
The sun's position is real. For every five minutes of the day the game works out the sun's height above the horizon (its altitude) and its compass bearing (its azimuth) with the equations of the NOAA Global Monitoring Laboratory's solar calculator, the same ones behind the other sun tools on this site. Then each shadow is plain geometry: a point h above the ground throws its shadow h ÷ tan(altitude) away from it, on the far side from the sun.
| Sun's height | Umbrella rim, 2.0 m (6 ft 7 in) up | Sail corner, 3.0 m (9 ft 10 in) up | House, 6 m (19 ft 8 in) high |
|---|---|---|---|
| 15° | 7.5 m (24 ft 6 in) | 11.2 m (36 ft 9 in) | 22.4 m (73 ft 6 in) |
| 30° | 3.5 m (11 ft 4 in) | 5.2 m (17 ft 1 in) | 10.4 m (34 ft 1 in) |
| 45° | 2.0 m (6 ft 7 in) | 3.0 m (9 ft 10 in) | 6.0 m (19 ft 8 in) |
| 60° | 1.2 m (3 ft 9 in) | 1.7 m (5 ft 8 in) | 3.5 m (11 ft 4 in) |
| 75° | 0.5 m (1 ft 9 in) | 0.8 m (2 ft 8 in) | 1.6 m (5 ft 3 in) |
A flat shape keeps its own outline on the ground, just moved: an umbrella's canopy throws a circle the canopy's size, shifted away from the sun. A sail or an awning has corners at different heights, so each corner moves by its own amount and the shadow is the shape they make. A house or a fence throws the outline of its foot joined to its moved top. A tree's crown, taken as a ball, throws an ellipse that stretches as the sun gets lower. A guest counts as shaded when their seat is inside a shadow.
Two worked examples from the levels. At 1 pm on 21 June in London the sun is 62° up, so an umbrella rim 2.0 m (6 ft 7 in) high puts its shade 2.0 ÷ tan 62° = 1.1 m (3 ft 6 in) away from the pole. At 7 pm the same day the sun is 19° up in the west-north-west, and a sail corner 2.1 m (6 ft 11 in) up puts its shade 2.1 ÷ tan 19° = 6.3 m (20 ft) away, back toward the house. The sun and shadow planner does the same sums for your own garden at any hour.
The ten levels
| Level | Where and when | Noon sun | What it teaches |
|---|---|---|---|
| 1. First shade | London, 21 June | 62° south | Shade falls away from the sun |
| 2. Lunch for four | London, 21 June | 62° south | The shadow swings round the table |
| 3. Phoenix in July | Phoenix, 15 July | 78° south | A near-overhead sun still moves the shade |
| 4. Follow the sun | New York, 1 August | 67° south | Morning shade lies west, afternoon east |
| 5. A north-facing garden | London, 10 July | 61° south | The house is the shade |
| 6. A south wall | Chicago, 15 July | 70° south | An awning shades the strip under it |
| 7. West patio, evening | London, 21 June | 62° south | Low sun gets under a roof |
| 8. Sydney at Christmas | Sydney, 25 December | 80° north | South of the equator the sun is in the north |
| 9. Use the trees | Atlanta, 1 August | 74° south | A tree is free shade, and it moves |
| 10. Winter sun | London, 21 December | 15° south | Low winter sun and long shadows |
The noon heights are the game's own figures from NOAA's equations; they follow the rule of thumb that the noon sun stands at 90° minus the latitude plus the sun's declination, which runs from +23.4° in June to −23.4° in December. London is at 51.5°N, so 90 − 51.5 + 23.4 = 61.9° on 21 June and 90 − 51.5 − 23.4 = 15.1° on 21 December.
The pieces, and what they are based on
The pieces are sized from real products so the shadows are the right size. The prices are game coins, set to make the choices matter, not shop prices; for real costs see types of awnings and what they cost and shade sail, awning or pergola.
| Piece | In the game | Based on |
|---|---|---|
| Umbrella | 2.7 m (8 ft 10 in) across, rim 2.0 m (6 ft 7 in) up; 20 coins | The 9 ft octagonal Shademaker Libra: 8 ft 10 in (2.7 m) across the corners, rib ends 6 ft 5 in (2.0 m) up when open |
| Triangle sail | 3.6 m (11 ft 10 in) sides; 30 coins | Coolaroo's 3.6 m equilateral triangle |
| Square sail | 5.4 m (17 ft 9 in) sides; 45 coins | Coolaroo's 5.4 m square |
| Sail posts | 3.0 m (9 ft 10 in) or 2.1 m (6 ft 11 in) tall; 10 coins each. Corners on the back wall sit at 2.7 m (8 ft 10 in), on a tree at 3.0 m (9 ft 10 in), free | The game's own heights |
| Awning | 5.5 m (18 ft) wide, reaching 3.1 m (10 ft 2 in) from the wall, 2.6 m (8 ft 6 in) up at the wall and 2.1 m (6 ft 11 in) at the front; 40 coins | SunSetter's range: widths from 8 to 20 ft, reaching 10 ft 2 in from the house; the heights are the game's own |
| House | 6 m (19 ft 8 in) high | The game's own |
Real sails are hung with one side lower than the other so rain runs off and the fabric stays taut, which is why the game lets you set the post height; how to install a shade sail covers the fixings and the slope, and the shade sail planner works out a real one. For umbrellas, how to choose a patio umbrella and the umbrella size calculator; for awnings, retractable or fixed awnings and the awning size calculator.
What the game leaves out
Shade is not the whole of sun protection. The game counts anything in a shadow as fully shaded, but UV also arrives from the open sky. In a study on a Tuscan beach, a beach umbrella that blocked the direct sun still let through a UV index close to 2 on a sunny summer day, because of the diffuse UV that arrives from the open sky. In a randomized trial at a Texas lake beach, people who spent 3½ midday hours under an umbrella got more sunburn than those who wore SPF 100 sunscreen, and the authors concluded an umbrella alone may not be enough. The NHS says to spend time in the shade between 11 am and 3 pm from March to October in the UK, and the EPA says the sun's UV is strongest from 10 am to 4 pm in the US. The UV index guide goes further.
Fabric. Real shade cloth lets some light through, and how much depends on the weave and the colour; the fabric comparer sets the fabrics side by side, and how to clean outdoor fabric and how to clean an awning keep them working.
The rest. Every day in the game is cloudless, the ground is flat, a guest is one point on their seat, an umbrella's canopy is taken as flat at its rim, a sail does not sag, and the neighbors' houses and trees are not there. The sun is followed every five minutes, and a guest who is in the shade at one tick counts as in the shade until the next.
Using it in your own garden
The ideas carry straight over. Find which way your garden faces with the garden-facing tool; read how the sun moves across your garden for the why; in a south-facing garden, the best shade for a south-facing garden; in a hot place, shade for hot climates; for an adjustable roof, the louvered pergola guide; and indoors, shading windows to cut cooling costs.
Sources: NOAA Global Monitoring Laboratory, solar calculation details (the sun's position); Shademaker, Libra specification; Coolaroo, 3.6 m triangle and 5.4 m square; SunSetter awnings; Safety and Health at Work, 2022, beach shade in Tuscany; Ou-Yang et al., JAMA Dermatology, 2017; NHS, sunscreen and sun safety; EPA, sun safety tips. Checked 19 October 2026.