I am at the programming stage of development. Here is my image I use for programming light shows. I will use it here to describe gameplay. In short Greek Gods is a point game with multi-ball goals. The left upper quadrant is Poseidon's Realm, and right upper Olympus. The powerball controls the diverter. When it is on the left the diverter sends the ball to the left ramp. Right goes right.
Hits to Poseidon's Realm charges up points on that area that when they reach a threshold qualify the Poseidon lock. Hit the scoop target to then activate the lock for one ball. This resets Poseidon points and the qualifying process repeats for a second ball. To release the balls for a 3 ball multi ball the scoop target drops to invite a shot to the scoop. Repeat shots to the orbit activate the Poseidon orbit magnet and will drop the ball in that area. This is handy because the whirlpool magnet will usually block balls shot from below. Remember the Poseidon slings are under manual control with flipper buttons increasing the skill/fun factor for that area. With good sling control the area can be qualified in 1 or 2 balls to that area. Oh, I forgot to mention that the points melt away in Poseidon's area so you have to keep on task or lose progress.
The same process applies for the Olympus side pops but there is no manual control on them, of course. It takes 3 or 4 balls to that area to qualify the lock.
Controlling the power ball is the tough part, though. If one of the locks is qualified but the power ball gets hit to the wrong side, you need to move it back again to get the ball to lock, otherwise it just goes down the wrong side of the ramp. But a clever player can get both locks qualified and filled up at the same time by shifting the power ball back and forth. Then a scoop shot can release a 5 ball multi ball.
Hitting the spinners 100 x qualifies Super Spinner mode. This invites a scoop shot (again by dropping the smart target) to turn on the mode. Super spinner runs atop all the other modes and gives additional Poseidon Points and Olympus Points allowing qualifying to happen more quickly. Each hit to a spinner gives a gentle pulse to the knocker making a very satisfying tap along side the standard sound effect. When this mode is active, every 25 spin hits invites a timed ramp shot that collects a bonus. But if you don't make the collect bonus shot or drain a ball, Super Spinner mode ends.
The 3 right side drop targets activate the hidden sling. This livens up game play. Hit the hidden sling 3 times and mystery award activates. This starts a light show on the serial orbit LEDs to invite a right orbit shot that when made activates the post at the top of the orbit up diverting the ball into the subway. Mystery award is meant to help the player progress in the game by a point award (meh), activating super spinner, switching the activated lock if the power ball ended up on the wrong side, activating a lock if nothing already started. It can also give an instant 3 ball scoop multi ball shooting balls from the shooter lane to the top of the orbit t the subway and ejecting all balls from the scoop 1,2,3. Also mystery can activate hydra battle.
Hydra battle is normally qualified by repeated hits to the central insert activating the proximity sensor. Hits change the color of the hydra inserts and after 28 the battle is qualified. A scoop shot starts the battle. Every 3 hits to the insert launches another ball getting up to 6 balls in play. Lose a ball and hydra gets away and the player finishes out the multi ball with whatever was earned. But, if you keep all six ball in play long enough to reduce hydra health down to 0 there is a light show and point award.
How about that underworld? If the player makes a point threshold after draining the last ball on the upper playfield the player's soul goes to the underworld. The game there is to make 3 shots to each of the 4 "rivers" (see page 1) meaning 12 loops total. On the first river shot (say left lower entrance) the magnet pins the ball and Hades laughs at you. The second shot is allowed to pass from lower left and out the upper left. The third shot and all subsequent shots are accelerated by the magnet. These rules apply to the other 3 "rivers." Complete all the rivers and you return from the dead and get an extra ball on the upper playfield. During underworld play bats fly across the screen, the light do weird things down there and it seeks to be creepy.
I still have many more modes to program like locking on the subway, ball saves activated by repeated ramp hits etc. I expect to be programming and animating in my spare time for years.