Navigable map idea: left, right and down. 4 squares wide, 3 tall. Go left with left shots when not in a mode, go right with right shots, go down with a scoop or gobble hole. Delve into a dungeon. Each square is a monster. Travel down at the bottom and you warp back to the top.
Completing a row or column unlocks something, maybe a "level boss".
There's a "nemesis" enemy who roams around the dungeon who you can run into. He moves one square whenever you move around the dungeon clockwise around the border of the map. Or he moves one square towards you every other square you move. If you wait until after you've beaten some guys he gets more valuable.

Optional multiplayer interactivity aspect:
Modes remain completed or partially completed between players. Once all of them are completed there's a special multiball and then you restart.
So players want to complete something (rows, columns, everything) if they know they can, but not leave anything 'almost completed'.

I actually had this idea in my notes folder! Great minds think alike!
"Combine demo man handles with the addams family shocker grips" (The Addams Family shocker game, not the pinball machine).

A mode-completion bonus that builds up with switch hits (or something) and carries over from player to player. But not from game to game. And players could bid on its starting value. It's downward bidding. The person who bids the lowest value goes first in the four player game. It's collected whenever the player completes a mode.

A Shadow the Hedgehog-type branching tree map where what shots you hit in the mode indicates what mode you get next. A bit like Roy in the Rick and Morty pin.

Two opposite roving arrows that meet in the middle. Shoot when they overlap for more points.

Two roving arrows that move together, side by side. When they reach the orbit they "overshoot" a little so that for a second or two only one of the two is visible. Shoot the one lit arrowduring that second for more points.

I had a game idea called "The Infinite Cycle of Love and Heartbreak" where each mode would be a different story of love in a different setting with different characters followed by some form of betrayal or tragedy. Each mode would have two sections, with the first being a multiball and the second being single ball play where your shots would be higher based on how well you did in the multiball. Or maybe the other way around, I guess.

Having an untimed multiball every mode might be too many multiballs. Maybe they'd need to be timed or single ball. I'm not really crazy about the idea of a game with lots of timed multiballs.