2000 Honda Civic, 170,000 miles. Was driving, and the car stopped accelerating?

Was driving when the car stopped accelerating while I was pushing the pedal. Engine still revved, RPMs still went up. I coasted until I stopped and parked the car. Then I started the car again, was able to drive forward for about 500 feet into a safe parking lot and it happened again.

Transmission related I suspect but I wanted some more knowledgeable opinions.

Yup, from your description is sounds like simple transmission failure. What is the exact cause? Only a transmission technician could properly answer that question after a complete and thorough transmission inspection.