One of my pet peeves with popular epic pinball games is that success can be predicated more on endurance than remarkable achievements. If you get far enough to start hitting the late-game extra ball gravy train, then you'll do well because you'll have enough resources to hit the risky shots the requisite number of times. Medieval Madness is probably the worst offender I can think of -- it's basically bash everything n times, and all the clutch moments are just about getting enough extra balls to grind through it. Twilight Zone can play out this way too, even though the ostensible rule set is much broader. Pound those ramps and start enough modes, it will be a good day, regardless of how much you put into the modes.
This is my one and only problem with Timeshock. To get to the Unknown, you're going to have to beat eight Explore modes (a LOT of side ramp shots), fill the time drive four times (even more treacherous left/right ramp shots) and win a mess of multiballs. All that is stitched together with some of the best moments and rules in pinball (it's obvious where Simpsons got its reverse flippers from; google will tell you that Keith played Timeshock back in the day). But dang, the best games I've had all had insane extra ball counts in common, and it was basically just obscene play time that got me my one legit (IIRC) trip to the Unknown.
I'd really like to see a preset in the reboot that caps the extra ball count and tightens up the busy work -- something tournament-setting-ish but with the big payoff reachable by mortals. Maybe make Tachyonium requirements and fragment locks tougher but empty continents and time drive charging easier. I tried to do this back in the day with the old operator's menu settings, but I couldn't ever quite get it right. Maybe score balance that emphasizes solid mid-game play over story progress would be nice too, but I never really dug deep into the scoring balance.
For reference, games that I think do a great job of rewarding setup and virtuosic clutch play would be Cirqus Voltaire, Doctor Who (shallow but it does shallow good), Black Knight 2000 (ditto), and Safe Cracker. (Safe Cracker is the only pinball machine I ever bought. It is much, much better than it seems at first. It is probably Lawlor's finest game by far.)