Control two computers at the same time with one keyboard and mouse

Hi - can someone give me tips on appropriate hardware to control multiple computers at the same time with a single keyboard and mouse. I don't want to control only one at a time (standard KVM or VNC sharing) - I want the cursor at the same point on both screens (two PCs, two monitors, identical resolutions). The goal is to control multiple MMO game clients at the same time. Also, if anyone can explain how to expand this to 3,4,+ computers, that'd be great

Thanks, CL

Other sites have explained that this is impossible - multiple USB hosts (the PCs) cannot simultaneously access the same USB device, because the protocol is serial. I found "USB servers" which allow multiple PCs to access USB devices (printer, webcam, etc.) but there isn't simultaneous access.

I've looked at PS/2 splitters and there's plenty to connect multiple PS/2 devices to one PC, but not the reverse.

Any KVM switches that aren't switches, but splitters?

All of this for MMORPG greatness? Meh.

with 4 mice and keyboards

interesting and cool, i didn't think there was a software solution for this