The backglass shows almost everything needed to play the game, and the score and instruction cards fill in the gaps. That said, they are extremely featureful games.
The numbers at the bottom of the glass show you what you will win in each colored line. The smallest number is the amount for three in a row, the middle number is for four in a row, and the top is for five in a row.
The features on the backglass give the player control to change the layout of the number card on the backglass, and hopefully reposition things appropriately. Each letter corresponds to a button on the footrail. The letters have to be lit, and the first ball has to be in play before the footrail buttons allow the player to move those quadrants/sections.
With A-F, every number on the backglass can be physically moved or rotated. This is particularly powerful for the center number, 16. Rotating that to the easier 13 allows for more connections, so I typically try to acquire through letter D and then rotate that one into center. However, the center number only applies to the green odds. The rotating numbers can only be moved until shooting the indicated ball. After fifth is best, and allows you to win in multiple colors.
Shooting a number or two adjacent squares gives you the best set up for a 3-in-a-row. Capitalizing on that takes skill and dedication. The ability to purchase a chance at receiving an extra ball can be helpful, but it's important to be mindful of how much you're spending to acquire one extra chance. Depending on how things line up and the mechanical portioning involved, it can take more than a dollar to get a single extra chance.
Beach Time also includes 'stop 'n shop', which allows you to play the game to a certain point, then put in more money to try to increase your odds.
The Ballyhole feature, when lit, gives you A-F on your -next- game. It's a carryover feature.
Beach Time was the last traditional Magic Squares game that Bally made, and in my opinion, one of the most generous and helpful to the player. Earlier games allowed you to rotate the numbers in the corners, or were missing the F line, lacked stop 'n shop, etc. There is one game Bally made after this that utilized the Magic Squares, Bonanza, and it is a very different game in many ways.
The instruction card on the left shows what the features do and when to use them, the score card on the right shows the reward for using those features skillfully. The gameplay is very tense and difficult. You have to modify the balls' path on the fly to achieve the number you desire, or bring it all the way to the bottom to be reshot. Hitting the wrong number means that your entire strategy might need to be rethought.
There's nothing quite like them in the world of pinball.