Sandbox is a unique map in the Halo 3 multiplayer experience due to its tiered design. The map features three vertical layers. The first layer is a brightened sandy dune surrounded by a dark expanse. It is designed primarily to host big team battles. Everything on this level is customizable and arrangeable. Unlike Sandtrap, the guardians of Sandbox instantly kill the player if he/she attempts to leave the main area of the map. In the center of the map lies a tile that can be removed in forge to access the bottom layer, known as the Crypt. The Crypt is a smaller, enclosed area that is empty by default. It has been dubbed the unofficial "official Grifball arena" by both fans and Bungie alike, but it can serve any mapmaking purpose. The final tier is the skybubble, accessible through an immobile teleporter on the middle level. The skybubble, roughly three times as large as the middle level, is a completely open forge area designed for mapmakers to have virtually unlimited creativity. As the title suggests, the skybubble is suspended over the middle tier, thus allowing the user to create aerial maps similar to Ascension and Lockout from Halo 2. All three levels of Sandbox can be played on simultaneously, while each featuring the grid system in the forge to help designers align their objects.
The unique features of Sanbox allow there to be multiple variants of the map featured in matchmaking. So far the accounted variants (Playlist, Variant) are:
- Mythic Playlist, Tundra - Tundra is a smaller, enclosed map built in the bottom level known as the Crypt.