From Kerbal Space Program Wiki
Sandbox mode is one of the available game modes in Kerbal Space Program. Sandbox differs from career mode in a number of ways:
- All parts start out unlocked, nothing is required to gain access to them.
- No restrictions are placed on the use of mod parts in vehicles.
- The science system and related parts do not function. Crew reports, EVA reports, and surface samples cannot be gathered, and attempting to observe experiments will not earn the player anything. Also, the Research and Development Facility cannot be accessed.
Until version 0.22, Sandbox was the only mode available in the game.