The Sandbox did not activate when I opened Sandbox mode, which I had already unlocked, but it did activate directly after re-completing level 12. It did seem unusual that although I had previously completed the entire game, I had to complete levels 12 and 30 again for the quests to activate. This is one of my favorite recent games, and these levels do not take more than a minute to complete, so it required little effort to complete them over again, but it is strange that it would save all of my progress and still not activate the quests automatically upon entering the game.
I encourage everyone to play, create and post sandbox levels to challenge yourselves further in this game. Many of the sandbox levels users have made are significantly harder than all of the campaign levels.
I do find it strange, because it should have registered as YES instead of NO since I had already completed both levels before the quests were added, and all 30 levels were still unlocked when I opened the game. Not that I know anything about programming.
2/2. Way too easy/quick. Finished the game once when it came out, so I only half-randomly clicked the inputs. Took me 8 minutes to finish the game this way.