We just received word from Valve Software that the company has released a free Steamworks Software Development Kit.

Steamworks is set of publishing tools that developers can use to modify their title to take advantage of the company’s digital distribution platform, which apparently has access to about 15 million gamers.

Included tools cover an in-game backup utility, pre-loading, anti-cheat, key authentication, copy protection, auto-update, multiplayer, social networking.

Valve is obviously gunning to become the Electronic Arts of digital distribution, since game developers can use Steam free of charge, and royalties for distribution are actually affordable. Steam currently has more than 300 games in its catalogue, including titles from developers such as Epic, id Software, Infinity Ward, Lionhead Studios or publishers such as Activision, Eidos, PopCap, SEGA, THQ and others.