I still have a VHDL version lying around from my old student project. :)
Wasn’t the original “written” using discrete logic (as in, no ROM)? How close to the original is your VHDL version then?
Since it's a student project to learn about VHDL and synthesis the pong clone had a few additions like simple math-expression based textures and we ignored trying to get close to the exact movement behaviour. But you actually get to control it with rotation based input. :)
In regards to ROM. It was an FPGA, meaning it was reprogrammed on every startup. But all behaviour was built as logic without accessing any memory.