0:00 - Sonic Adv. 2
0:50 - calisthenics
5:08 - dang cannon boss
10:00 - tootin' horns
20:06 - ballistic penguins
28:40 - carpet bombing boss
37:53 - Sonic Advance 3
41:15 - chaos 'n stuff
43:36 - hot in the city
55:58 - hammer where do I hurt 'im
1:15:50 - game over
They start out somewhat innocuously but soon graduate up to criminally inscrutable boss fights and throwing me into pits.
So, having tried most of the official 2D Sonic games--except the xDS ones--I'll now go back to the first one I tried, which seemed at the time derivative and like I should play the games it was aping first: Sonic Mania. Well, I've played those games, and aside from Sonic 1, from which it didn't borrow as directly anyway, they were unpleasant to the player. So I suppose I can understand now why people think so highly of Mania, since it at least isn't all insane on your buns. It's a low bar for Sonic fans.
I put the three Sonic Advance games up on eBay for one lowball price and they sold within minutes, so that was cool.
1