Keep the Light guide
How to play Keep the Light
Keep the Light is an idle game about a coastal lighthouse. You light the lamp by hand, add helpers that keep it shining, and look after ships through every season. Its twist is keeping watch: of all our games, it is the one most at home with being left alone, because it can keep earning for a full day while you are away.
The basics
- Light the lamp. Tap the big button to make a glimmer. Every lighthouse starts with a single flame.
- Add helpers. Oil lamps, polished lenses, foghorns, lifeboat crews and harbour lights all make glimmers on their own, every second.
- Buy upgrades. At 10, 25, 50 and 100 of a helper, an upgrade doubles it. A few upgrades double the whole lighthouse.
- Keep watch. Three night-watch upgrades make your lighthouse keep earning for longer while you are away: from 12 hours to 16, 20 and finally 24.
- Hand over the watch. Once the light is strong, you can pass the lighthouse to the next keeper and start fresh with logbooks. Each makes everything 6% stronger, for good.
Your first few minutes
- Light the lamp until you have 15 glimmers and set up an oil lamp. Glimmers now arrive by themselves.
- After 25 taps, Dry matches appears. It doubles every tap.
- Save for a polished lens at 100 glimmers. With five helpers, Fresh whitewash doubles the whole lighthouse.
- With ten helpers, Night watch appears: your lighthouse now earns for 16 hours while you are away.
How the night watch works
In every Littleby game, your helpers keep earning while you are away, up to a limit (usually 12 hours). After that, the game waits for you. We explain why in idle games that work offline.
Keep the Light lets you push that limit back:
- Night watch adds 4 hours, for 16 in all.
- Storm lantern adds another 4, for 20.
- Keeper’s cottage adds a final 4: a full day.
Like other upgrades, they reset when you hand over the watch, so you buy them again each watch. They are cheap compared with what they earn: with the cottage, a lighthouse checked once a day never misses an hour. When you come back, the welcome-back message tells you how long your light can now shine without you.
Tips
Buy the night watch early. It does not make your light brighter, but it makes every long absence count for more.
Check in once a day. With all three watch upgrades, once a day is enough to collect everything.
Use Buy 10 and Max. Buying in bulk is handy after a long break. Your choice is remembered.
When to hand over the watch
Handing over unlocks once you have made 40 million glimmers in the current watch. Logbooks are worked out as the square root of this watch’s glimmers divided by ten million, rounded down, so your first handover brings at least 2. 160 million glimmers brings 4, and a billion brings 10.
A good rule is to hand over when it would add at least half again to the logbooks you hold and progress has slowed. A handover just before a long time away is often a good moment, as long as you buy the night watch again straight away. For more, see what is prestige?
Keep your lighthouse safe
Keep the Light saves automatically in your browser every 30 seconds and when you leave. Use the Save page to copy a backup now and then, or to move your lighthouse to another device.
The numbers
These tables come straight from the game's own data, so they always match what you see in the game.
Helpers
| Helper | First one costs | Glimmers each second |
|---|---|---|
| Oil lamp | 15 glimmers | 0.5 |
| Polished lens | 100 glimmers | 3 |
| Foghorn | 1,100 glimmers | 20 |
| Lifeboat crew | 12,000 glimmers | 130 |
| Harbour light | 130,000 glimmers | 850 |
Each helper you buy costs 15% more than the one before.
Helper upgrades
Each doubles what one kind of helper makes.
| Upgrade | Appears at | Costs |
|---|---|---|
| Trimmed wicks | 10 oil lamps | 243 glimmers |
| Clean chimneys | 25 oil lamps | 1,975 glimmers |
| Whale-free oil | 50 oil lamps | 65,019 glimmers |
| Steady flame | 100 oil lamps | 70,458,807 glimmers |
| Soft cloths | 10 polished lenses | 1,618 glimmers |
| Brass fittings | 25 polished lenses | 13,168 glimmers |
| Prism rings | 50 polished lenses | 433,463 glimmers |
| Great lens | 100 polished lenses | 469,725,380 glimmers |
| Deep note | 10 foghorns | 17,800 glimmers |
| Bellows | 25 foghorns | 144,843 glimmers |
| Echo chamber | 50 foghorns | 4,768,093 glimmers |
| Famous horn | 100 foghorns | 5,166,979,183 glimmers |
| Oilskins | 10 lifeboat crews | 194,187 glimmers |
| Rowing drills | 25 lifeboat crews | 1,580,110 glimmers |
| Sturdy hull | 50 lifeboat crews | 52,015,557 glimmers |
| Lifeboat station | 100 lifeboat crews | 56,367,045,634 glimmers |
| Painted stripes | 10 harbour lights | 2,103,690 glimmers |
| Harbour wall | 25 harbour lights | 17,117,855 glimmers |
| Pilot boat | 50 harbour lights | 563,501,870 glimmers |
| Twin beacons | 100 harbour lights | 610,642,994,364 glimmers |
Other upgrades
| Upgrade | What it does | Appears at | Costs |
|---|---|---|---|
| Dry matches | Each time you light the lamp counts twice. | 25 glimmers brewed by hand | 100 glimmers |
| Keeper's steady hand | Each time you light the lamp counts three times. | 250 glimmers brewed by hand | 2,500 glimmers |
| Fresh whitewash | Everything at the lighthouse shines twice as bright. | 5 helpers | 500 glimmers |
| Calm seas | Everything at the lighthouse shines twice as bright. | 150,000 glimmers this season | 200,000 glimmers |
| Lighthouse board visit | Everything at the lighthouse shines twice as bright. | 20,000,000 glimmers this season | 35,000,000 glimmers |
| Night watch | The light keeps shining 4 hours longer while you are away (16 hours in all). | 10 helpers | 1,000 glimmers |
| Storm lantern | The light keeps shining 4 more hours while you are away (20 hours in all). | after Night watch, 100,000 glimmers this season | 150,000 glimmers |
| Keeper's cottage | The light keeps shining 4 more hours while you are away: a full day in all. | after Storm lantern, 10,000,000 glimmers this season | 15,000,000 glimmers |
Achievements
- First light: Light the lamp for the first time.
- A steady flame: Set up your first oil lamp.
- Heard for miles: Install your first foghorn.
- On watch: Buy the night watch.
- Round the clock: Buy the keeper's cottage, so the light shines a full day while you are away.
- A busy coast: Have at least one of every helper.
- A thousand glimmers: Make 1,000 glimmers in total.
- A million glimmers: Make 1,000,000 glimmers in total.
- A billion glimmers: Make 1,000,000,000 glimmers in total.
- The next keeper: Hand over the watch for the first time.
- Old salt: Reach watch 6.