Unity3D has a tile map system that allows you to make 2D maps with no programming at all. This tool is available for free with the unity base package and can be expanded with the 2D extras package found in unity’s GitHub. It’s fairly easy to use but if you are not careful when setting it up you could have a hard time.
After importing a sprite sheet into your project. Unity allows you to divide the sheet into individual tiles. To do this you click on the sprite sheet and look at the inspector, the texture type should be “Sprite (2D and UI)” and the sprite mode set to “Multiple”. To start the division process click on the Sprite Editor button. During this process there are a couple factors you should take in account:
Pixels per unit : Before even going into the Sprite Editor make sure that the value of the “Pixels Per Unit” parameter on the inspector is the same size of your tiles. E.g: if your sheet is holding 64×64 px tiles then make the “Pixels per unit” 64. If you forget this step your tiles will have padding or overlap each other.
Pixels Per Unit: 「Sprite Editor」に入る前に「Pixels Per Unit」のパラメータがタイルのピクセルサイズと同じにしないといけません。例えばスプライトシートに64px✖64pxのタイルが入ってたら、「Pixels Per Unit」を64に設定してください。設定が違うとパディングがはいったり、タイルが重なったりします。
Pivot: When using the slice tool in the Sprite Editor. Make sure to set the pivot to “center”. If you miss this step the tiles will be offset from the grid in the scene.
Sprites are just the visual part of our tiles. Without colliders, even if we can see the ground,our characters would just fall off the world. Unity made it very easy to add colliders to your grid. Just select the tilemap and add a “Tilemap Collider 2D” component to it. This is fast and easy but it creates a collider for every tile with a sprite on it. This means that even tiles surrounded by other tiles that will never be in contact with anything will also have a collider. I.e: A lot of unnecessary colliders that will never be used and useresources are being created.
To prevent this, we can add an other component. The “Composite Collider 2D” component. This component requires a little bit of setup. When this component is added to your tilemapGameObject, it automatically adds a RigidBody2D component to the object. If you are adding collision to static objects like the ground or a wall, make sure to set the “Body Type” of the RigidBody2D component to “Static” or it will fall down with gravity. Now go back to your “Tilemap Collider 2D” component and tick on the “Used By Composite” box. This will merge you colliders leaving only the outer colliders.
これを防ぐためもう一個のコンポネントを付けられます。「Composite Collider 2D」というコンポネントです。追加するときに自動でRigidBody2Dが追加されます。もし動かない物のコライダーを作っているときに（床、壁、など）RigidBody2Dの「Body Type」を「Static」にしないと重力で落ちます。最後に「Tilemap Collider 2D」の「Used By Composite」を選択することで内側の無駄なコライダーがなくなります。
Rule tiles also make it easy to create tile animations.
One thing to take care of when setting up this rules is the order you add them to the list. When unity is checking your list of rules it stops and selects the first sprite that fulfills the rule. So if you have a more specific set of rules after a very general one, it might be ignored.
Getting the tiles to work as you intend them to, might take some time but once you have it set up, it will speed up your map making time. And if you decide to change a sprite midway through the map design, you can just change the sprite for that rule without having to touch the tiles in the scene.A good rule of thumb is to keep the tiles with very specific rules at the top of the list and the more general ones at the bottom. And remember you can drag the rules up and down within the list to change the order easily.
Layers are powerful tools that help us keep rendering orders separate, make pretty overlaps and set colliders to some objects while ignoring others. But it’s important you keep track of the layer you are working on at all times, because just as any other software that uses layers like Photoshop or Gimp, editing the wrong layer will cause you problems. So if you run into some weird behavior like colliding into clouds, falling through the ground or tiles not animating correctly, make sure you check everything is on the right layer. To help you with this Unity has an option to gray out all layers except the one you are working on. This option can be turned on by changing the “Focus On” parameter located on the Scene window to “Tilemap“.