Here are some obvservations I can do after several playthroughs of the game:

• 'Restart level' keeps your coins and lives the same and gets you back to checkpoint if you hit it. Ideal for farming lives, if needed. Also, pausing and pressing 'Restart level' is a good reflex to have if you're about to die in a pit (saves a life and skips death animation). It gives you the powerup state you had last time you finished a level or died.

• 'Save and quit' doesn't actually save and quit lol. It has the same effect as closing the game mid-level. The game updates the savefile only when you finish a level, meaning that by pressing 'Save and quit' and loading game afterward, you'll have the exact same coins, lives and powerup state as when you finished the previous level.

• Block collisions is weird. Make sure to never run on ground that has 1-tile wide holes. You have about 50% chance to just fall in the hole. Even though a lot of levels have some parts where you are expected to run over 1-tile wide holes, because it works in regular ST, it doesn't work properly in the current version of this game.

• For ILs or practice, use the savefiles I put in Resources. It's explained there how to use them, you'll be able to start at any level you want, with the powerup state you want, and 99 lives. Pro tip: you can close the game during the level complete animation, which will make the savefile not update.

• Sometimes my Right input gets dropped, so Tux suddenly stops almost like he hit a wall and I have to release and press Right again for it to work again. This is an issue I haven't had on my first playthrough, and it actually makes the game unspeedrunnable. If anyone has experienced that issue and managed to fix it, I'd be very glad to know about it.