The code is available on GitHub, and both games together total up to slim 5MB of data. Now, that source code is finally available, giving modders a much better idea of how the originals work heading into the Command & Conquer Remastered release date.
A few weeks ago, EA announced that it would release the source code for both the original Command & Conquer and Red Alert, as part of an effort to help the community build better Command & Conquer Remastered mods.