How to play Invaders
Invaders is a remake of the 1978 arcade shooter. Five rows of eleven aliens march side to side across the sky, stepping down a row every time they reach an edge, and you have one laser cannon on the ground to stop them.
Clear the whole formation to start the next wave, and keep going until your cannons run out or the aliens land.
Rules
- The formation steps sideways, drops when it reaches either edge and turns round. The fewer aliens are left, the faster it marches: the last one is quicker than your cannon.
- You have one shot in the air at a time. The aliens drop bombs, up to three at once; a bomb that hits your cannon costs you a life. Your shot can knock a bomb out of the air.
- Four bunkers give cover, but every hit chips them, from either side, and aliens marching through a bunker wipe it out. They are rebuilt at the start of each wave.
- You start with three cannons and earn one more at 1,500 points. If the aliens reach the ground, the game ends however many cannons are left.
- The bottom two rows are worth 10 points, the middle two 20 and the top row 30. The saucer that crosses the top of the screen is worth 50 to 300. Each new wave starts a little lower and marches a little faster.
Controls
- ← → / A D
- Move the cannon
- Space / ↑ / W
- Fire (hold to keep firing)
- Mouse
- The cannon follows the pointer; hold the button to fire
- Touch
- Hold a finger where you want the cannon; on-screen pad on phones
- P / Esc
- Pause
- Enter / Space
- Start
Tips
- Clear the formation from the sides: the narrower it is, the longer it takes to reach an edge and step down.
- Fire from under a bunker’s edge, then step out of the way of the bomb coming back.
- Every miss keeps your one shot busy until it leaves the screen, so take aimed shots rather than holding fire.
- Leave the last few aliens for when you are lined up: once they speed up, they drop fast.
Invaders strategy
The march speeds up
With all fifty-five aliens the formation takes a step about every 0.6 seconds; each alien you shoot shaves roughly a hundredth of a second off that, and the last one steps every 25 milliseconds, faster than your cannon can follow. Each wave also marches 7% faster than the one before, down to 60% of the first. So never leave a scattered handful for the end: the more aliens left over late, the faster everything above you drops.
Shoot the edges first
The formation only steps down when its outermost living alien touches a side. Clear whole columns on the left and right and the block narrows, so it walks further before each drop and you get more time per row. The bottom row decides when they land, and later waves start up to four rows lower, so keep an eye on the lowest alien rather than the count.
Count your shots for the saucer
The saucer appears every 18 to 26 seconds while at least eight aliens are left, from the left if you have fired an even number of shots that wave and from the right if odd. Its value follows your shot count: the 8th shot of a wave scores 300 if it hits, and so does every 15th after it (the 23rd, 38th and so on). Any other shot scores 50 to 150. With only one shot on screen at a time, counting is easy.
Bunkers and bombs
Only the lowest alien in each column drops bombs, half of them aimed at the column above your cannon, and no more than three are ever falling. Bombs and your own shots both chip the bunkers, so firing through a bunker digs a slot you can then shoot through while still mostly covered. Your shot also destroys a bomb it meets, which is a last-second save, not a plan: it costs you the shot.
About Invaders
Space Invaders was designed by Tomohiro Nishikado and released by Taito in 1978. It was one of the first games with a high score worth chasing, its marching aliens sped up only because the hardware drew fewer of them faster, and in Japan it was popular enough to start the lasting legend that it caused a shortage of 100-yen coins.
This version is an original remake inspired by it, with the same rows of aliens, crumbling bunkers, mystery saucer and one-shot cannon, plus mouse and touch controls.
Questions
Is this the original Space Invaders?
No. It is an original browser game inspired by the 1978 Taito arcade classic, free and with nothing to install.
How do I play on a phone?
Hold a finger where you want the cannon and it slides there and fires; an on-screen pad with left, right and fire appears on phones.
How is the score calculated?
Aliens in the bottom two rows are worth 10, the middle two rows 20 and the top row 30. The saucer is worth 50 to 300, depending on how many shots you have fired that wave.
Why do the aliens speed up?
The formation marches faster the fewer aliens are left, as in the original, so the last alien of each wave is the fastest thing on the screen.
