Hello, and welcome to cdfreaks
Unfortunately, I don’t think that it’s possible to do what you’re thinking about due to the nature of the way that distributed computing works. Basically, a problem that involves extremely large numbers of simple, but independent, calculations can be split into component parts and then farmed out to multiple workstations with the results being returned in a non time-critical manner. The trouble with modern games is that they are extremely time-critical and most of the calculations are interdependent and if the results aren’t there when they’re needed, the game will crash or, at the very least, drop frames and provide poor gameplay. There’s also the problem of network bandwidth/speed which would have a major bottleneck at the interface with the primary workstation. Also, even if this were possible, the game would have to be rewritten specifially to work on a platform of this nature.
I have heard of some projects to use hundreds/thousands of obsolete CPUs all linked together (as if on the same motherboard) but this requires a totally different architecture to that of a standard PC, and again the game would have to be rewritten.
If you ever find a way to make it work, I’m sure we’d all love to hear about!