I recently replayed through
Sonic Spinball, and while I like it probably a lot more than most people, I have only beaten it twice in my entire life, and the reason for that is because the final level, "The Showdown" is a poorly-designed mess designed to frustrate the player and waste their god damned time.
The first problem comes from the starting area. Here is a map for reference.

The designers clearly want you to collect the Chaos Emerald in the center first by breaking a series of blocks below it by pressing the buttons on either side. To prevent you from leaving, they placed a couple of bird robots at the top that will funnel you towards some ramps that will send you back to the starting area. Sounds good
on paper, but in practice, there's numerous problems with this.
First, the wonky physics combined with the ability to influence Sonic's air momentum with the D-pad means that it's entirely possible to sequence break the designers' intention of keeping you locked in this area. In fact, in all my experience of playing this game, it's actually
more likely to occur due to the semi-random nature of pinball, as well as the fact that the buttons on the side of the Chaos Emerald are in a bitch of a place to hit consistently. Indeed, this Chaos Emerald is usually one of the last ones I end up collecting thanks to this.
Second, even if you collect the Chaos Emerald behind those blocks, if you die during the stage, you will still have the Chaos Emerald (thank God), but the blocks will have respawned, meaning you have to go through the rigmarole of breaking the blocks first.
Third problem with this area, unrelated to the Chaos Emerald itself, is the "Safety Rocks" on the death chutes on either side of the flippers. See those series of three cyan rectangular targets on either side of this area? If you hit all three of them, you will activate a "Safety Rock" which will launch you out of the death chute and prevent you from dying. However, since the intended path for trying to sequence break involves the player getting funneled down the death chute and getting launched by a Safety Rock anyway, every time you accidentally attempt to leave (a common occurrence since this is a
pinball game), you will activate the Safety Rock (even if you don't have one) and the targets will be reset, effectively wasting your Safety Rock every single time and putting yourself at risk.
But once you manage to get all the Chaos Emeralds, the bullshit has still yet to end, as you still have to contend with the final boss.

This entire boss is designed around the notion of knocking you out of the boss room. The idea is that you're supposed to turn off his "defenses" by pressing a button on the bottom of Eggman's cockpit, which consists of either a hand that will drop you down into an area you need to spindash back into the arena, or a wind sock that will knock you into a window that will eventually crack and send you flying out of the arena, forcing you to climb
all the fucking way back up to the boss area.
The first issue is a technical one, since the resolution of the game isn't large enough for you to tell when his defenses are down and you can hit him. Every time you press the button, it just prints a Robotnik face to the ticker, which doesn't tell you one way or the other if his defenses have been lowered. The only way to know is to launch yourself up the ramp, which will probably end up getting you caught in a wind sock and knocked against the windows and out of the arena, forcing you to come climb all the way back again.
However, they
will tell you if his defenses are back up, since if you either press the button while his defenses are down -- on purpose or accidentally, and believe me, you
will hit it accidentally -- or take too long to attack Eggman's cockpit, the ticker will output "Smell my socks!" Well, if you were kind enough to tell me when he
isn't vulnerable, why weren't you equally kind to tell me when I
can hit him, instead of having to take the scientific route and end up getting knocked out for the fifteenth time and having to waste ten fucking minutes just trying to get back to the boss area?
I fucking hate this level. It's an unfun, poorly-designed mess in what's otherwise a fun and quirky game with excellent music. I fully endorse anyone playing this game to just turn off the game once they get to this level, because this isn't so much "difficulty" so-much-as a tedious waste of time. It's as if the designers knew their game was only four levels long and decided to make the last one as bullshit as possible to pad out the game's playtime.