Let's see... Always jumping on loops in Sonic 2, spindashing repeatedly at level ends, spindashing before Eggman or Zazz in Sonic Dash, repeatedly spindashing DURING Eggman or Zazz. I always bounce attack on City Escape and Final Rush rails to increase my speed. I always spam Tails and Eggman's guns rather than target anything. I unintentionally always suck at Sonic CD's special stage 4 and have to grind time UFOs. I always accidentally discover Sonic's air dash and homing attack in the Advance games. I always Up+R on the ramps in Advance and Rush. I always use Ancient Light on the Golem in SA2. Not a lot else I can say.
I always beat Robotnik in Labyrinth Zone. Always. No better feeling than giving that fat man what he deserved. I don't do the fake transition stuff but I do spindash like mad, repeatedly while waiting for the next act to happen. I always activate the Megajump glitch in Oil Ocean. I always activate the no gravity glitch in Carnival Night. Makes for some fun shenanigans.
At the beginning of the Aquatic Ruin boss, I like to hop on one of the totem poles and see how long I can fight the boss on top of them until I get forced off.
I tend to jump in the middle of loops in attempt to gain a bit more speed after landing on the slope below. It's always a very satisfying and helpful trick whenever I manage to time it properly.
I always do the teetering thing on the edge of the Prison Eggs, too. Let's see... When fighting Robotnik in Mushroom Hill 2 as Sonic, I'll wait for the engines to shut off before hitting him, simply because it's more fun (and seems more fair) than running up underneath the ship. I'll often go for a perfect on every special stage in S3&K by collecting all the rings. I like to stand on top of the blue discs in Marble Garden before spin dashing, to see Sonic bounce off while still in his revving-up animation. Speaking of Marble Garden, I always try to beat Robotnik at the end without letting Sonic fall off the screen.
Let's see... I always take the secret upper path in Chemical Plant Act 2. Always. Going up that underwater shaft traumatized me so much when I was little, and ever since I discovered the alternate path, I developed the habit of always taking it. In Sonic 3 and Knuckles, I would wait until I have 100 rings until I turn into Super Sonic. I always was afraid I couldn't keep my ring count up so I made sure to collect A LOT before transforming. I feel this habit is gone now for the most part. I always spindash under Silver Sonic in DEZ when he lands to get some easy hits, and let go at the last second before he spins. In Casinopolis, I always lose the pinball games with less than 100 rings, go through the sewer, collect TONS of rings, and avoid getting hit all the way through. I find this method faster, although risky.
Oh I've got one more for SA2. Whenever I have to jump off a tall object (and time is not an issue of course), I do a somersault jump.
Ditto. Double-ditto. Triple-ditto. Same here. I've gotten over it, though, so I don't really take the special route. Oh you. *quietly walks out of the room, grinning*
I do a lot of the habits which have been mentioned in this topic. I also do the following: Sonic 1: I like to try and beat Sonic 1 without dying once, without losing any rings once and I try collect as many lives as possible. My record on the mobile version is 55 lives. Here's a screenshot from my android phone; Sonic 2: Once I've beaten Eggman in Emerald Hill act2, I always jump over the wheels which scatter from Eggman's vehicle wreckage. The wheels of course can't hurt Sonic but I fill compelled to avoid them. I like get at least one 150-ring jackpot before I finish Casino Night zone. I always take the secret upper route in act2 of Mystic Cave to avoid the dreaded pit. Well, I did until I played StealthTax's remasterd version. Now I feel drawn to the pit for some reason..... /> Sonic CD: When Metal Sonic kidnaps Amy at the start of Collision Chaos zone 1, I jump up to a higher ledge so that MS doesn't pass by Sonic. I like to finish zone 2 in the Good future so that it transitions seamlessly to the Good future of zone 3. I always feel compelled to visit the Angel statue in Wacky Workbench zone 1 (Past). Sonic 3&K: When knuckles presses the switch at the end of Angel Island act 2, I jump to the left when the bridge breaks so that Sonic doesn't fall down. I then look up at Knuckles who never stops chucking. I always try to collect 999 rings (the maximum amount you can collect) in each act in Sonic 3&K (which you can achieve thanks the generous amount of rings awarded in the Glowing spheres bonus stage). I also like to see how quickly I can reach 99 lives. At the beginning of Mushroom Hill act1 after the cut-scene where Knuckles suspiciously closes a door with a switch; I then jump on the switch with Sonic to open the door to the giant ring. I jump on the switch again - so the door starts closing - and then immediately spindash so that Sonic makes it to the giant ring just before the door closes. Sonic is trapped in the area with the giant ring!
I always have to get all the Toxic Caves rings in 16-bit Spinball. I don't know why, I just do. I also seem to have a habit of being impatient with platformers and it has cost me so many lives. I always have to bust certain 1-up monitors in 16-bit Sonic 2 as well. Picky gaming is picky.
Thanks to your playthrough on the Sonic-A-Thon (and I believe you also did this on the FTCR playthrough?) I saw what that was like for the first time after reading about it in the manual for that game. I wasn't missing out on much.
Without any logical reason, Skidding is my habit because I find it stylish. (that goes for every Sonic game)