Quake changed more than just game hardware. Its code was so well written that it’s still used in games today. Bits of the original Quake code run under the hood in the Call of Duty games, including the upcoming Modern Warfare 3. Valve’s engineers were familiar with the Quake engine when they were creating the Source engine that powers everything from Half-Life 2 to the upcoming Dota 2. “We licensed Quake to Valve when they were starting their company and they built Source using Quake, and Quake code is still in Source even today. Inside of some DLLs, there’s still some Quake code running in there,” says Romero.
In fact, Quake was so well-written that aspects of it haven’t required changing in fifteen years. Says Jay Stelly of Valve, “We had access to Quake & Quake II when building Source and we definitely made use of that. Some of the Quake code does its job just fine even today.”