Invalid Tangram is a space shooter with a twist. Instead of just flying around shooting space ships, you can use your defeated enemies to give yourself extra powers to give yourself a better chance of getting further in the game. The controls are simple, the arrow keys more you around the screen, and the space bar makes you shoot.

Enemy space ships will fly around, shooting at you. Enemies come in one of four different colours: red, blue, green, and yellow. If you manage to shoot down an enemy, it will turn into a block (of the same colour it was before you shot it down), and fall to the bottom of the screen. Soon you will have a lrge number of blocks piling up, and here's where the power-up system comes into play.

As soon as there's two or more blocks of the same colour touching each other, you can absorb them, using the left shift key, and get a power up. The power you get depends on the colour of the blocks. Red blocks will let you fire faster, blue blocks will give your shots more power, green blocks will make your shots home in on enemies, and yellow blocks will give you a spread shot, with three instead of one bullet.

The power-ups are only temporary, and the more blocks you've absorbed, the longer the effect will stay. You can also absorb other powers while one is still active.

• Invalid Tangram website