A common Synthetic Environment for training (Individual, Collective & Pre-Deployment) is available through Titan CSE (Common Synthetic Environment). Land, Sea, Air and Space are not separated but are a seamless virtual continuum that allows operations anywhere on the globe; from the ocean floor to the Earth's Orbit, in individual domains or simultaneously.
Titan CSE is all about scale, and scalability. Using the powerful Outerra rendering engine, blades of grass and dirt roads are as eye-pleasing as in any major video game, yet the view from 50,000 feet is as good as in any high-end flight simulator.
This open-philosophy approach, which has really only come of age in the last 5 years, amounts to a stark product discriminator against other popular simulation environments which tend to be fully closed due to the age of their underlying infrastructure or that they apply proprietary standards and business models.
Most available engines either allow the creation/modification of existing scenarios without the user truly being able to make a full product with its own identity, or on the other hand they are a full Software Development Kit (SDK) targeting developers who wish to build new systems from the ground up without offering any “Pick Up and Play” capability out of the box. Titan CSE, however, has been designed from day one to support both ends of the spectrum.