I noticed some confusion in posts about the number of widebodies Bally produced in the late 70s through early 80s, and found this bit about Embryon on IPDB:
"The fifth and last widebody pinball from Bally - not counting the limited run of "SuperPin" games from the early 1990s. EMBRYON was also the first Bally game to feature artwork by Tony Ramunni, and the first (and last) game from this company to use the trademarked "Flipsave" ball saving feature - a small flipper inside the right outlane used by players to flip lost balls back into the return lane. (according to Pinball Snapshots)"
Since I couldn't find (e.g., 30 seconds with google) a list of these games with their production dates, numbers, etc., I used IPDB's advanced search to generate a list of those 5 widebodies. Hope this helps someone down the road.
For comparison, here is how they score/rank on Pinside (at the time of posting):
Future Spa: 6.9
Hotdoggin': (No score, needs three more ratings)
Space Invaders: 7.1