Hashi (short from Hashiwokakero) also known as Bridges is a logic puzzle with simple rules and challenging solutions.

The rules are simple.
Hashi is played on a rectangular grid with no standard size. Some cells start out with numbers from 1 to 8 inclusive; these are the islands. The rest of the cells are empty. The goal is to connect all of the islands into a single connected group by drawing a series of bridges between the islands. The bridges must follow certain criteria: They must begin and end at distinct islands, travelling a straight line in between; They must not cross any other bridges or islands; They may only run orthogonally; At most two bridges connect a pair of islands; and The number of bridges connected to each island must match the number on that island.
Are you lost? Check out the step by step tutorial

Zooming
Pinch with two fingers to zoom in/out. If you use a mouse you can use the scroll button.

Moving
Tap and drag to move the puzzle. If you use a mouse you can click and drag with the middle (scroll) button.

Drawing bridges
Just tap/click between 2 islands. You can also tap/click an island and drag towards another island.

Game modes and sizes

• You can change the game you play from the "hamburger" menu at the top-right corner.
• You can change the mode / size of the current game from the top menu (click on the down arrow at the top/middle)
• There are 2 modes which you can play
  • Random - this mode loads a random puzzle from the chosen size
  • Quest - this mode requires you to login. You can then solve a sequence of puzzles with increasing difficulty.

Other helpful tips

• You can get rid of the address bar and gain extra playing space by dragging the header or the footer quickly upwards so you scroll the page a bit down. It's tricky and you need practice. iOS8+ users - this will be just temporary until you click something in the bottom bar - sad story I know.
• If you are left handed or just playing with your left hand there is a spacial option in the settings just for you.
• Try the different helpers in the settings - some will make the puzzle too easy for you, others may automate some trivial tasks.