GOG is giving away the classic RTS "Total Annihilation" and its expansion this weekend. Travel back in time to 1997, when humans and AI faced off against hundreds of vehicles and robots.

When "Total Annihilation" came out, the genre took a giant leap forward, raising the bar with its massive scale, realistic physics, and true line-of-sight guidance. While its legacy may not be as tangible as "Command & Conquer," there are several attempts to build on it, such as the new "Supreme Commander" in the store.

Supreme Commander: The "Gold Edition" and "Supreme Commander 2," which include the excellent "Forged Alliance" expansion, are available and on sale for 80% and 75% discounts, respectively. The sequel is good, but the previous title is recommended, especially if you want to buy the expansion.

Total Annihilation will be free to play until June 7 at 2:00 pm (9:00 am CST). If you're interested in its history, check out our feature on the making of Total Annihilation.