Found 2 ratings (with comment) on this game

A fast and fun game. Another gem from Ted Zale.

Rock Makers sees Bally really hit it's design stride and show us a bit of what is to come.

The Pros:
An upper flipper that splits the pf and adds a layer of playability never seen before in playfield design. Zipper flippers on the lower PF require attention and two sets of aiming skills. The lower PF may look sparse. But those tic-tac rollovers give you 10 difficult targets to hit. You CAN hit the right rubber bumper from the left flipper and get all targets in a single shot. I have gotten up to 8. Light the 200 from the upper flipper and keep it up there as much as you can from the right orbit shot. The artwork can be disconcerting for some, but I find the artwork of Jerry Kelly (and Christian Marche's craft as well) to be something that immediately says "pinball" more than just about anything else. This game offers more than what one may originally think by a long mile.

The Cons:
Those slings will make you curse and cry like a child. Most copies that I have played speak in German.

The Takeaway:
A challenging game that never really gives you the win. You will always be reaching for more with this design. A true player by Master Zale! It is on the "WANT" list.

Update:
A second set of scoring for spelling out An arc of mini-rollover buttons in lower playfield spells out R-O-C-K M-A-K-E-R-S. This adds another aspect of gameplay rules to the game design. Each player has a Rock-A-Rock single yellow score reel on the backglass to count the number of times either R-O-C-K or M-A-K-E-R-S is achieved. This game is a different kind of pinball game. I love it!